>it's hidden behind a couple of touch screen actions involving small virtual buttons and it does not pull over immediately

It was on the home screen when I've taken it, and when I tested it, it seemed to pull to the first safe place. I don't trust the general pubic with a stop button.

I feel like this ends with drunk morons accidentally creating Waymo barricades and totally ruining Mardi Gras

Can you not just unlock and open the door? Wouldn't that cause it to immediately stop? Or can you not unlock the door manually? I'd be surprised if there was not an emergency door release.

Imagine how many drunk/careless passengers might press it. Stopping in the middle of the street or highway could be a serious safety hazard.