You’re right there should be a minimum safety threshold before tech is deployed. Waymo has had pretty extensive testing (unlike say, Tesla). As I understand it their safety record is pretty good.
How many accidents have you had in your life? I’ve been responsible for a couple rear ends and I collided with a guard rail (no one ever injured). Ideally we want incidents per mile driven to be lower for these driverless cars than when people drive. Waymos have driven a lot of miles (and millions more in a virtual environment) and supposedly their number is better than human driving, but the question is if they’ve driven enough and in enough varied situations to really be an accurate stat.