If the child lived in a neighborhood where cars went slower (it was a 25mph zone) he wouldn't have gotten hit in the first place. Praising Waymo here is like praising a priest for not molesting a child. Yes it's good that the waymo slowed down more than the average car, but really the whole system should be completely rethought. Instead, we're pouring billions into single occupancy vehicles, when we should've been pouring billions into high speed rail, subways, etc.
I'm hopeful that waymos converge on a more efficient design and improve cities in general. As it stands, they are a way for the rich to commute without having to exchange pleasantries with the underclass.