This seems like an argument that you should be more worried about getting in a Waymo if there is a safety driver than if there isn't. If so, that would definitely be an interesting conclusion.
This is missing the point. Just because we accommodate certain types of errors by humans, that doesn't mean should or would tolerate them if the same errors were made by machines. (Or vice-versa, for that matter.) The standards we hold machines and humans to can be very different, and that should be expected.