Good thing no one blamed the kid.
Did you miss this sentence? How can you read it in any other way?
Yes, I blame the parents or the adults that were supposed to supervise the child (but not the child). I teach my kids not to run into the street. I also watch them like a hawk near streets because kids are dumb.
I agree with you that we have too strong of a car culture. But we do. So until that changes, we need to teach our kids and adults to be vigilant.
But while we do that, I'd still rather have Waymos around than human drivers.