It also seems like they should control for the demographic subset of riders that own Teslas. It seems possible that affluent car owners have factors at play that affect the likelihood of a fatal accident vis-a-vis the global average.
Just compare Teslas fatalities per mile with and without autopilot.
Remove the mileage driven from the cars that have never used autopilot, to control for drivers too cautious to trust their lives to beta software, and you should have your demographic.
In fact, there is a study which suggests that affluent car owners drive more recklessly than not so wealthy ones. Here's an article about it:
http://usa.streetsblog.org/2013/07/16/study-wealthier-motori...
I remember reading a more detailed article about the study somewhere but I can't find it right now.
Also autopilot can only be used in certain scenarios (freeway driving). Are hours driven by autopilot in this ideal environment being compared with millions of hours spent driving in non-autopilot-eligible roads/conditions?
Autopilot _should_ only be used on divided highways. However in practice it can be activated on most roads as long as there are lane markings. It's up to the driver to assess the driving conditions and decide whether it's safe to activate Autopilot.
