Perhaps the comparison should only be to other taxis. Since I cannot buy a Waymo, it is not really relevant whether it is better than an average driver (including all the drunk ones, and the speed racers, etc).

There are other safety differences with human-driven vehicles… interpersonal violence does happen with taxis (e.g. drivers sexually harassing/assaulting passengers, passengers robbing drivers) - by definition those things cannot happen with a Waymo