Waymo already does this.. well it doesn't stop and wait, it's proactive.

Waymo reports teen riders for bad behavior and delivers them to the police (60 points, 1 month ago, 31 comments) https://news.ycombinator.com/item?id=48824010

Those "teen riders" were shooting toy guns at the passer-by.

As someone who walks on the streets / uses public transport, Waymo was 100% in the right there. Wish all taxi services were like that.