Well, more so that people are terrible and they would steal a video game (and deprive the next person of that game) for minimal profit. I could see people trying to steal seats (I’m sure they will secure them), but far more likely scenario I’m thinking about is people trashing the cars.
Whether it’s drunk teenagers, belligerent ex Uber drivers etc. people burn those electric scooters or through them into the ocean. People sadly cannot be relied on to be remotely decent.
That said, with a bit of vetting all of this is taken care of. For example they could require you to take a photo of your ID and yourself with the ID in the frame etc. just something to discourage the worst of society from ruining everything.
Final thing: they might verify your face which would be somewhat dystopian. Like Face ID for Waymo. Hardware is relatively cheap so should be workable.