That is the most puzzling thing to me. Not from a technical, but societal ( https://en.wikipedia.org/wiki/Tragedy_of_the_commons ) point of view. Compare with public mass transit, except of Singapore, Japan, it is mostly dirty, in spite of cleaning staff working hard, and other people around. In a Taxi/Uber you have the driver watching, and other rentals are usually inspected after, and immediately before next rent out, just to make sure.

Not so in car-sharing pools, and there it's already materializing as a problem. How do you solve that with your 'robo-cab'? Tapping on dirty/smelly in your app, send back to garage? What if you notice it only 5 minutes after you started the trip, already robo-riding along? What if you have allergies against something the former customer had on/around it? Or was so high on opioids, that even a touch of the skin could make you drop? As can, and did happen. How do you solve for that without massive privacy intrusions? Or will they be the "new normal" because of all that Covid-19 trace app crap?