Most of the time, human beings driving cars with their own hands and eyeballs are not "liable" for their errors (unless they can be proven negligent or drunk), unless you count their insurance going up. Most car accidents do not end with anybody getting arrested, or sued, or anything like that. Insurance pays out, premiums go up, case closed.

If Waymo can be proven negligent or something, then sure, bleed em dry. But as long as they're acting in good faith and significantly reducing overall road fatalities per mile driven, I think it's actually pretty unreasonable to try to hold them to such a high standard you end up subjecting society to more of the higher fatality rates caused by humans.