I imagine that the next user would just tap a button on their smartphone saying that the car is dirty, upon which the car drives back to a service center and the user receives a new car (not the same car).
The problem with this is, as a rider, I personally would not want to have to be constantly expecting a dirty car. If one out of every 3 cars has vomit or syringes in it or feces, I would personally stick with a service that has human drivers at the wheel.
This is remedied with a service charge for the responsible person.
Unlike a Tenderloin sidewalk, deterrents are easily enforced under a scheme like this.
Uber and Lyft currently charge $100 for a cleaning fee to the driver when their passengers soil a car's interior with vomit, etc. I don't see why Waymo, Tesla, or Uber would be any different.
Zipcar and Reach Now don't seem to have an issue with this, I would be surprised if it's any different when you don't have to the move the steering wheel yourself. If they can make a car that drives itself they can surely figure out a way to keep it clean.
Sure if one out of every three had vomit, syringes, or feces it would be a huge problem. One out of three seems incredibly unlikely and off by at least a couple of orders of magnitude.
Maybe this would self-regulate. If someone is the kind of person that would make a mess on an autonomous car ride, maybe after calling the service again and having to wait for a replacement due to someone else’s carelessness, their attitude would change.
1 in 3 seems ridiculously high. I'm not sure what the vomit-rate is currently for Ubers and taxis, but I'm pretty confident it's not even remotely close to 33%.
This seems solvable. As a rider, you have the option to select "This car is too dirty to ride" or "This car needs cleaning."
If you indicate it is too dirty to ride, the car reports for cleaning. If the cleaners agree with your assessment then your ride is free, paid for by the person responsible for the mess, who would also pay for the cleaning. If the cleaners don't agree, then you pay for the cleaning and your own ride. If you indicate that the car is dirty but want to ride it regardless, then the car could just check in for cleaning after your ride at no expense to you.
If you don't want to send the car away, perhaps you have an urgent appointment, you could just ride the messy car and have it cleaned after your ride. If adding a few extra minutes to your trip isn't a big deal, then the reward of having it be free may compensate you for the inconvenience.
A system like this would provide an incentive for customers to report dirty cars (saving money on their ride) and to leave cars clean (avoid paying for car cleaning). Those incentives are hopefully at least as strong as the incentives in place now.