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.)