Waymo's article from 2024 about these operations (“much like phone-a-friend”): https://waymo.com/blog/2024/05/fleet-response/
• (29 seconds long) https://www.youtube.com/watch?v=T0WtBFEfAyo
• (59 seconds long) https://www.youtube.com/watch?v=elpQPbJXpfY