The percent improvement doesn't really matter though. The fact that it is better than even just professionals still means that there are fewer crashes, and therefore they are improving overall road safety.
* In a better car, serviced much better than the average professional vehicle.
The % matters because it is close enough excluding these factors, so we can not definitely say it currently better than humans yet, close but not conclusively so.
That is not a argument against them. It is a simple function of economics, i.e. as long as it better than Lyft/Uber(they are already) that is the price point that Waymo operates at, so it is safer for most users and easy choice to make.
However if you can afford and regularly use high quality private livery car services then the data has to be lot clearer to make the switch.
