There was a recent video by a Waymo person who dealt with understanding the world. He went into great detail about how to observe things. One thing he mentioned is that the car also has the goal of getting to the destination. There was an example of a pretty packed school area. The safest thing to do might be to completely stop. The car however slowed down and tried to make its intentions clear. Unfortunately I cannot find the video.. it also went into detail of how to spot that something unexpected might happen.