Depending upon your statistical sources, US traffic fatalities are around 1.25-1.50 per 100 million miles. [1] All forms of real-world autonomous driving across all manufacturers across the world are still somewhere below 200 million miles, conservatively estimated. [2] [3] Between the Tesla and Uber fatalities, by these rough back-of-the-envelope numbers, autonomous of various grades is still roughly 2X higher than human drivers. Maybe 1X if you squint at the numbers hard enough, but likely not orders of magnitude lower. I don't anticipate rapid legislative and insurance liability protections for autonomous systems until we see orders of magnitude differences on a per 100 million miles driven basis, and that will take time.
Waymo racks up about 10,000 miles per day across about 600 vehicles spread in about 25 cities. [4] Roughly 3.6 million miles per year if they stay level, but they're anticipated to rapidly add more vehicles to their fleet. In the US alone, about 3.22 trillion miles were driven in 2016. [5] Don't know what a statistically valid sample size is based upon that (I get nonsensical results below 2000 miles, so I'm doing something stupid), though. If Waymo puts two orders of magnitude more cars out there, they'll still "only" rack up about 365 million miles per year, and not all the miles on the same version of software.
[1] https://en.wikipedia.org/wiki/Transportation_safety_in_the_U...
[2] https://www.theverge.com/2016/5/24/11761098/tesla-autopilot-...
[3] https://www.theverge.com/2017/5/10/15609844/waymo-google-sel...
[4] https://medium.com/waymo/waymo-reaches-5-million-self-driven...
[5] https://www.npr.org/sections/thetwo-way/2017/02/21/516512439...