When I drive and there's a child walking on the sidewalk, I'm not analyzing the chances the child will jump onto the road. I'm just assuming the parents have succeeded at explaining how to not kill yourself, without that assumption I would go crazy with too much things to worry about. AI does not get crazy, nor even tired, with too much tasks. It might usually come up with the same result that I always apply - just drive slowly through roads with children on sidewalks. But it might do something I won't do - slow down even more if the child seems to be doing something suspect.

One of the problems with Google-designed self-driving is that it goes slow and refuses to go if uncertain. I imagine that's why those cute little cars without driving wheel were axed. Even if the system has driven a bajillion miles without inflicting any risky situation, it won't sell if it can't guarantee doing your commute in your usual time. But it can't assume the same risk you take every day, that if that child behaves extra stupid and law misfires, then you might find yourself traumatized and without a driving license. Because when AI loses that license, it's killing the whole business. So, the bar for safety must be higher, slowing you down to a fully-controllable crawl, or constraining to high-safety situations. Hence, you get all those highway-assist features all over the place.

Disclaimer: I work in Google, but have no insider information about Waymo. Just remember these marketing materials back from the Chaffeur days and still think that was the way to go.