Waymos exceed human drivers on both metrics, thus it is reasonable to say that Waymos have reduced crashes compared to the equivalent average human driver covering the same distance.
Mistakes like this are very rare, and when they do happen, they can be audited, analyzed with thousands of metrics and exact replays, patched, and the improved model running the Waymo is distributed to all cars on the road.
There is no equivalent in humans. There are millions of human drivers currently driving who drive distracted, drunk, recklessly, or aggressively. Every one of them who is replaced with a Waymo is potentially many lives saved.
Approximately 1/100 deaths in the US are due to car fatalities. Every year autonomous drivers aren't rapidly deployed is just unnecessary deaths.