Agreed, the "cars become autonomous" problems are separate from the "autonomous cars means nobody owns cars anymore" ones.
I'm more optimistic about autonomy. It still seems like a crazy hard problem, but things are advancing so fast right now that it actually seems like they might get there.
But I don't see where the leap from "autonomous cars" to "shared cars" happens. The main obstacle there is simply personal: I don't think people want shared cars. People want autonomous cars (although they probably want the autonomy to be optional) so that hurdle is not a problem on that side.
I suspect that given peak loads, utilizations, etc. there are pretty unfounded assumptions about the economics associated with what would in effect be robo-taxis. Drivers today make, what, $10-15 per hour? So one would need to explain to me how taking that cost alone out of the equation suddenly makes using taxis and limos in place of private auto ownership an economically sensible thing for the majority of people in the majority of places where it isn't today.
The comparison is between a digital computer and an organic one (i.e. a human driver). Furthermore, one can't just assume that a car can drop a person off and head out to the suburbs to wait. That's a huge potential cost in both congestion and energy.
I'm more optimistic about autonomy. It still seems like a crazy hard problem, but things are advancing so fast right now that it actually seems like they might get there.
But I don't see where the leap from "autonomous cars" to "shared cars" happens. The main obstacle there is simply personal: I don't think people want shared cars. People want autonomous cars (although they probably want the autonomy to be optional) so that hurdle is not a problem on that side.