Read beyond the headline:
Waymo said its robotaxi struck the child at six miles per hour, after braking “hard” from around 17 miles per hour. The young pedestrian “suddenly entered the roadway from behind a tall SUV, moving directly into our vehicle’s path,” the company said in its blog post. Waymo said its vehicle “immediately detected the individual as soon as they began to emerge from behind the stopped vehicle.”
I'm guessing the automated car was able to react far faster than a human driver would have and the child would have sustained far greater injuries with a human behind the wheel. I'll wait for the full investigation though.