I agree with your general point, but you can't just join up 2 correlations like that, that isn't always going to work when there are other confounding factors (and there always are). Wealth also correlates with age which anticorrelates with reaction times and general fitness.
And not all markets are equally competitive. Just because insurance rates differ doesn't mean risks necessarily do the same way. And let's not forget that while insurers are professional risk assessors that doesn't mean they're infallible either, or immune to other distortions (e.g. pass-the-buck subprime mortgage kind of issues).
But at some point between wealthy and rich the person hires a (non-wealthy) driver and now they're back to square one.
All other factors taken into account, driving has become much, much safer in recent years, and is now safer than it ever was. When you start to use technology to eliminate driver errors in that self-same error-prone cohort, there's no reason to think that the safety dividend won't be even more pronounced than it is today.
If you want to link crash rates to wealth, you would also have to account for countries like Germany, that has a similar median wealth figure to the US, but a vastly lower motorway death rate [1]
It seems you can't both say 1) Tesla drivers are less likely to have accidents because they are wealthy and error-prone, and 2) Extending self-driving technology that eliminates basic errors to less-wealthy and/or more error-prone drivers won't have a net benefit on driver safety.
[1] https://www.sciencedirect.com/science/article/pii/S240584401...
Clearly /if/ Tesla self-driving code is safer than the average driver then extending that to the general driving population would be a net good. But if the apparent safety is an artefact of the statistics due to Tesla cars themselves being intrinsically safer just as practically every other modern vehicle is a safer car than one built 20 years ago then extending self-driving to every vehicle might not be a net safety benefit
Likewise, if the driver cohort is different (and we know that it is different) from the general population & that cohort is required to drive the vehicle precisely at the times that the self-driving code can't cope which are probably the times when driving places the most demand on the driver, then that different in driver cohort matters: the statistical difference in death rates could easily be a result of differences in driver populations.
You can't tell from the data as given & the fact that Tesla keeps repeating the aggregate figures in their PR is suspicious frankly.
(NB. that paper you link simply underlines my point - In both countries, the lowest wealth quartile has a vastly greater death rate on the roads than the rest of the population. It doesn't matter whether Germany is worse or better than the US. If Tesla draws disproportionately from higher income deciles, then we should a priori expect them to have a far lower death rate than the mean. Quoting the mean as a benchmark to compare the Tesla death rate against is outright misleading.)
Secondly, Tesla themselves makes it clear that their self-driving can't be relied upon to driver the car unsupervised - the driver has to be paying attention at all times in case the Tesla self-driving code decides to do something catastrophically stupid. Hence the same factors that correlate with driver attentiveness in the ordinary population will also affect the Tesla population. Wealth correlates with health correlates with better reaction times & general fitness.
The Tesla autopilot tends to turn itself off precisely in situations where driving is difficult and complex - which in turn implies that these human factors will remain just as important as they are in the general driving population.
(Of course it may simply be that the reason wealthy people have a lower death rate on the roads per mile is that they can afford cars that are safer in crashes; the above is my supposition, not evidentially backed.)