>all of the resources that are going into autonomous cars was instead going into proper public transit infrastructure.
They need not be separated. This is the entire point of the Cybercab and the Cybervan: Get self-driving cars, vans, etc. with the one job of moving people around. They only park to recharge or repair.
Demand is based on time of day/week/month/year.
Where do all those cars needed during peak demand go? They're going to be parked somewhere and it's not going to be in the middle of nowhere, because that's an awful customer experience.