A variety of things that may not have immediately come to mind:
Downtowns become more attractive to visit via robocar, by both suburbanites and "uptowners," when you don't need to find and/or pay for parking.
A tourist who arrives via robocar to a downtown hotel can eliminate the daily parking fee needed for storing their car. A city center hotel might then increase in attractiveness over a hotel on the outskirts of a city that offers cheaper or free parking. (See: WorldCons that are in driving distance, and then having to pay expensive hotel parking over five days for a car that you might not use at all during that time.)
Newly developed city center hotels may have fewer city regulations regarding the amount of available parking they need to provide. This could result in cost savings, more hotel capacity, and/or other side effects that could result in lower room prices for customers.
A trip on current mass transit bears many similarities to a trip in a self-driving car: You don't need to pay attention to the road, you can read, work, have conversations with others, etc.
Some people don't find travel time in general to be very productive time, so being able to get work done while being driven or transported is not universal. There are also many arguments against doing or continuing work while on the way to or from your place of employment (decompression/transition, not being paid because you're not "on the clock," etc.).
Many advancements in self-driving car tech can be applied to mass transit, too. (Driverless busses and trains lower the cost of operation, no driver fatigue, etc. Plus: Drivers won't be reporting late to work or a shift change, or taking too long a break; stop requests will always and automatically be fulfilled; late night services will be more reliable; vehicles can communicate without being distracted from driving and ensure that they're spaced out evenly, etc.)
Since there's no driver taking a cut or paycheck, robotaxis and/or shared car services may wind up being cheaper than current human-driven taxis, but due to economies of scale robobusses are sure to still have a big cost advantage for riders over robocars.
There are going to remain large masses of people who are not affluent enough to afford robotaxis and/or shared car services.
There are no one-way streets in an area that is restricted to robocars. There isn't even necessarily a "correct" side of the road to drive on. Even a narrow alley that's only the width of a single car is a two-way street for robocars. For a short alley it becomes temporarily one-way in the direction of travel of the first robocar that enters it, until it's clear of vehicles again. Alternately, and/or for longer alleys, robocars can enter and travel in both directions simultaneously as long as there are cutouts that allow them to pass each other at certain points.
Areas that are robocar-only will not have stop lights. They won't have specific pedestrian crossings on smaller streets, either. They may, however, still have marked pedestrian crossings on higher-capacity arteries, to minimize vehicle flow disruption.
People don't walk only for transportation. There are many people who walk or jog on streets for exercise. Dogs need to be walked. People with small children often like to put the kid(s) in a stoller and just "go out for some fresh air." People often "go out for a walk" to calm down, or clear their minds, or just for "a change or scenery" from the inside of their home/office/whatever.
People don't always have a single specific destination that they want transportation to. Often you want to get to a general area and then walk around (especially for tourism and downtown shopping).
In many places the percentage of foot traffic from people walking by due to having to park away from their final destination is actually very low. The point-to-point abilities of robocars will have negligible effect, there.
Personally, if robocars are available but I'm going only up to four or five blocks I wouldn't even think of calling a robocar, unless I needed to carry something. In fact, if I knew robocars were available to get me back to my origin quickly and easily, I might not think twice about taking a much longer, one-way walk. It's quite likely that I might want to initially go on foot somewhere (good exercise/fresh air/scenery/etc.) to get something, and then use a robocar to get me and my cargo (like groceries) back.
As the prevalence of robocars goes up, walking from place to place alongside and across roads with vehicles will become safer.
City dwellers who start having children will have less pressure to move out and into suburbs whose streets are "safer" from traffic accidents.
Having children in a city currently generally means the children will be taking mass transit to school, which parents regard with suspicion in regards to safety. Robocars suitable for use by children can eliminate this perceived risk in a city.
High housing density in a city provides a large nearby potential pool for both good teachers and talented students. With robocars suitable for use by children it'd be as easy and safe to send kids to a high quality magnet school across town as to a "shopped for" school many miles from home in the suburbs. A benefit of this is that the kids are physically closer to home, which tends to be reassuring to parents.
Just as now, property developers will have great infuence on how land is apportioned in robocar oriented developments. Without plotspace taken up by garages and driveways, it's more likely that developers will favor putting more plots into the same total area (thus, more profit) than giving people the same size plots with larger yards and more space between houses. A plot in a robocar oriented development area that's the same size as a current plot with a garage and/or driveway on it will probably be a "larger," more luxurious, and thus more expensive plot.
When one or the other end of your journey is near a rapid transit stop, journey time on transit is frequently about the same over the same distance as using a car. (I just used Google Maps to compare mid-afternoon driving vs. transit on routes between the San Francisco Civic Center and no specific street address in each of San Bruno/Daly City/Oakland/Fremont/Walnut Creek. I'm not sure if Google factored in traffic, since it's late and I manually adjusted the time to mid-afternoon. Google may have based the calculations on all road travel being exactly at the speed limit.)
Rapid transit will almost invariably remain cheaper than a robotaxi (economies of scale again). First and last mile robotaxis with rapid transit in the middle is likely to be the cheapest point-to-point method of travel where rapid transit exists and aligns with a major portion of your trip. During rush hours it avoids bottlenecks and chokepoints on roads, so there's a high chance that this will win on journey time at those times.
Large park-and-ride lots at transit stations can shrink once there are a lot of robocars. Shops/offices/homes built on the land freed up will automatically become Transit Oriented Development, and most likely will be robocar oriented development, as well.
A variety of things that may not have immediately come to mind:
Downtowns become more attractive to visit via robocar, by both suburbanites and "uptowners," when you don't need to find and/or pay for parking.
A tourist who arrives via robocar to a downtown hotel can eliminate the daily parking fee needed for storing their car. A city center hotel might then increase in attractiveness over a hotel on the outskirts of a city that offers cheaper or free parking. (See: WorldCons that are in driving distance, and then having to pay expensive hotel parking over five days for a car that you might not use at all during that time.)
Newly developed city center hotels may have fewer city regulations regarding the amount of available parking they need to provide. This could result in cost savings, more hotel capacity, and/or other side effects that could result in lower room prices for customers.
A trip on current mass transit bears many similarities to a trip in a self-driving car: You don't need to pay attention to the road, you can read, work, have conversations with others, etc.
Some people don't find travel time in general to be very productive time, so being able to get work done while being driven or transported is not universal. There are also many arguments against doing or continuing work while on the way to or from your place of employment (decompression/transition, not being paid because you're not "on the clock," etc.).
Many advancements in self-driving car tech can be applied to mass transit, too. (Driverless busses and trains lower the cost of operation, no driver fatigue, etc. Plus: Drivers won't be reporting late to work or a shift change, or taking too long a break; stop requests will always and automatically be fulfilled; late night services will be more reliable; vehicles can communicate without being distracted from driving and ensure that they're spaced out evenly, etc.)
Since there's no driver taking a cut or paycheck, robotaxis and/or shared car services may wind up being cheaper than current human-driven taxis, but due to economies of scale robobusses are sure to still have a big cost advantage for riders over robocars.
There are going to remain large masses of people who are not affluent enough to afford robotaxis and/or shared car services.
There are no one-way streets in an area that is restricted to robocars. There isn't even necessarily a "correct" side of the road to drive on. Even a narrow alley that's only the width of a single car is a two-way street for robocars. For a short alley it becomes temporarily one-way in the direction of travel of the first robocar that enters it, until it's clear of vehicles again. Alternately, and/or for longer alleys, robocars can enter and travel in both directions simultaneously as long as there are cutouts that allow them to pass each other at certain points.
Areas that are robocar-only will not have stop lights. They won't have specific pedestrian crossings on smaller streets, either. They may, however, still have marked pedestrian crossings on higher-capacity arteries, to minimize vehicle flow disruption.
People don't walk only for transportation. There are many people who walk or jog on streets for exercise. Dogs need to be walked. People with small children often like to put the kid(s) in a stoller and just "go out for some fresh air." People often "go out for a walk" to calm down, or clear their minds, or just for "a change or scenery" from the inside of their home/office/whatever.
People don't always have a single specific destination that they want transportation to. Often you want to get to a general area and then walk around (especially for tourism and downtown shopping).
In many places the percentage of foot traffic from people walking by due to having to park away from their final destination is actually very low. The point-to-point abilities of robocars will have negligible effect, there.
Personally, if robocars are available but I'm going only up to four or five blocks I wouldn't even think of calling a robocar, unless I needed to carry something. In fact, if I knew robocars were available to get me back to my origin quickly and easily, I might not think twice about taking a much longer, one-way walk. It's quite likely that I might want to initially go on foot somewhere (good exercise/fresh air/scenery/etc.) to get something, and then use a robocar to get me and my cargo (like groceries) back.
As the prevalence of robocars goes up, walking from place to place alongside and across roads with vehicles will become safer.
City dwellers who start having children will have less pressure to move out and into suburbs whose streets are "safer" from traffic accidents.
Having children in a city currently generally means the children will be taking mass transit to school, which parents regard with suspicion in regards to safety. Robocars suitable for use by children can eliminate this perceived risk in a city.
High housing density in a city provides a large nearby potential pool for both good teachers and talented students. With robocars suitable for use by children it'd be as easy and safe to send kids to a high quality magnet school across town as to a "shopped for" school many miles from home in the suburbs. A benefit of this is that the kids are physically closer to home, which tends to be reassuring to parents.
Just as now, property developers will have great infuence on how land is apportioned in robocar oriented developments. Without plotspace taken up by garages and driveways, it's more likely that developers will favor putting more plots into the same total area (thus, more profit) than giving people the same size plots with larger yards and more space between houses. A plot in a robocar oriented development area that's the same size as a current plot with a garage and/or driveway on it will probably be a "larger," more luxurious, and thus more expensive plot.
When one or the other end of your journey is near a rapid transit stop, journey time on transit is frequently about the same over the same distance as using a car. (I just used Google Maps to compare mid-afternoon driving vs. transit on routes between the San Francisco Civic Center and no specific street address in each of San Bruno/Daly City/Oakland/Fremont/Walnut Creek. I'm not sure if Google factored in traffic, since it's late and I manually adjusted the time to mid-afternoon. Google may have based the calculations on all road travel being exactly at the speed limit.)
Rapid transit will almost invariably remain cheaper than a robotaxi (economies of scale again). First and last mile robotaxis with rapid transit in the middle is likely to be the cheapest point-to-point method of travel where rapid transit exists and aligns with a major portion of your trip. During rush hours it avoids bottlenecks and chokepoints on roads, so there's a high chance that this will win on journey time at those times.
Large park-and-ride lots at transit stations can shrink once there are a lot of robocars. Shops/offices/homes built on the land freed up will automatically become Transit Oriented Development, and most likely will be robocar oriented development, as well.