Some no frills car sharing companies make their users clean the car. And if you get a dirty car you can order a new one and the previous driver gets billed. And small one person Robo cars could also be build much simpler and cheaper.
Correct, you'll be rating the previous passenger in your Uber's once we have self driving vehicles. Same mechanics will apply.
There could well be discriminatory billing - clean conscientious passengers pay less than drunk party goers.
Sure. My basic point though is that, given high utilization, $15/hour doesn't really change the economics of ordering a car on demand though. It still makes sense in the cities where it already makes sense unless services like Uber are already being blocked for regulatory reasons.
Cities where Uber and the like are being blocked with oppose robo-cars even more vigorously. Like the revolts against steam engines and factories we read about. Uber-opposition will seem like a practice exercise.