Earlier quoted context omitted.
As I mentioned in a previous thread some time ago, where does this notion of self-driving cars suddenly meaning shared cars come from? To some people these things seem to be joined at the hip.
Because the self driving aspect enables dispatch. Prompting a human that is also driving to make a 3 block detour is pretty hard to do safely. Prompting a passenger to see if they will take a 3 block detour to save cost is not so hard to do safely. The self driving vehicles would also be reporting available ride shares to people looking to make trips.
You'd pay a subscription for a certain level of car service (time responsiveness, cargo capacity, comfort level). Maybe you'd get a discount for scheduling your commute a week in advance.
The # of cars on the road might be the same, but the amount of resources we would consume as a society would be lower. Or maybe it would be the same, but the flexible model would allow scenarios that weren't previously possible (e.g., your child could "drive" to school without you).