And it is not the child’s or their parents’ fault either:
Once you accept elementary school aged children exist, you have to accept they will sometimes run out like this. Children just don’t have the same impulse control as adults. And honestly even for adults stepping out a bit from behind an obstacle in the path of a car is an easy mistake to make. Don’t forget that for children an SUV is well above head height so it isn’t even possible for them to totally avoid stepping out a bit before looking. (And I don’t think stepping out vs. running out changes the outcome a lot)
This is why low speed limits around schools exist.
So I would say the Waymo did pretty well here, it travelled at a speed where it was still able to avoid not only a fatality but also major injury.