It does? Those drivers remove a small portion of the autopilot miles driven, but a large portion of the challenging/dangerous miles. The result are stats with a low accident per mile ratio.

It definitely skews the statistics. Compare two driver's records, but use all the driving of the first, and only the driving on safe/clear/clean/visible sections of highway for the second. Voila: the second will very probably be the "better" driver.

Sure, but the important question is the capability of the Autopilot, not the Tesla driver.