We absolutely do know that Waymos are safer than human drivers:
Waymo’s self-driving cars put people in harm’s way something like 80% to 90% less often than humans for a wide range of possible ways of measuring “harm’s way.”
It remains to be seen whether Tesla’s autopilot or self-driving features (currently at Level 2 autonomy) will exceed Waymo’s success, but early returns look very promising. That’s future where cars become significantly safer.