Has Waymo been responsible, in any material way, for any deaths? To my knowledge they have not. (from a quick search: their cars have been involved in one fatal collision total, where a "SUV rear-ends stopped vehicle behind stopped Waymo at high speed, one passenger in the human-driven car and animal declared dead", a situation in which their car was obviously only peripherally involved)
I have no idea. I never suggested they have already happened, but I am certain that they will.