One concern I had is that once self-driving cars are widespread people might take advantage and treat them poorly with no human driver watching. Where a human would likely notice and deal with weird smells or things added by the past customer. Waymo-type service probably rely on reporting by passengers once the car already arrives, no? (I've never driven in one)

People might be treating them nice today because Waymo is a fancy new service in Jaguars that people treat as a novelty. Once those e-taxi services are under aggressive economic demands I'm curious to see how it plays out.