Isn’t a self driving car fleet essentially the same as self driving public transit? Self driving cars can pick the most efficient routes to get everyone where they need to go, in a way that would not be possible if a human driver is required.
What's so special about efficient routing with a driver-less car? There's no route that a human driver couldn't follow just as well if assisted by GPS software.
Putting people on a train is going to be far more efficient.