You are missing the point. Tesla is the industry leader in fatalities primarily because they have such a huge lead in the number of miles. Miles are not directly comparable to each other because each company has a different approach, but Tesla's fatality rate is 1 every 800 million miles. Waymo appears to be the leader among the rest of the industry with 20 million miles. How can you predict Waymo is safer than Tesla at this point? They may end up being safer, but it is way too early to say that right now.
And that problem gets worse with increasing data, not better, because the useless data will drown out the important data.
Tesla's own legal filings shows that Autopilot is 2-3x more likely to get into accidents that Teslas without Autopilot engaged. (The 2x for Autopilot disabled but other advanced driving features engaged; 3x for all advanced driving functions disabled.) https://www.forbes.com/sites/bradtempleton/2020/10/28/new-te...
Their marketing claims are just that: marketing.
Waymo has 20 million miles using multi-modal sensory data: cameras, LIDARs, etc. Because the sensory data is gathered in multiple modes, it can be cross-referenced and calibrated against each other even if the placement of individual components change (so long as not all components change at the same time), meaning that the data can be used across multiple models.
Tesla has 4 billion miles using a single mode of sensory data, but because it uses a single mode of input (visual), old data becomes mostly useless when they make any changes to the system, such as to the visual resolution of the cameras, or their positioning on the vehicles. This is one of the big reasons that they get so many regressions with Autopilot.
Also, despite having 4 billion miles of sensory data, that hasn't stopped Tesla from being the industry leader in self-driving fatalities. The rest of the industry combined has only a single fatality.