Not all "miles driven" are the same. Autopilot is going to be engaged on highway driving which already has a lower accident rate per mile driven. So that biases a simple comparison.
Edit: and even within highway miles, autopilot will be enabled more in the "easy" stretches and turned off in roadworks etc.
Precisely. If these systems aren't or can't be engaged on a Pittsburgh street at night in a whiteout, then I don't much care.
Tesla jukes the stats by "Oh, this won't go well, so we're not even going to try", which isn't an option for human drivers, short of "don't drive at all".
On similar roads, in similar traffic, in similar weather.
If you look at fatalities or define “accident” as cases where somebody had to visit a doctor or something like that, you also need to compare to similar cars. Most self-driving cars are relatively new and relatively large, and both decrease those (probably even accident rate because they statistically have newer brakes and tires and have more active safety features)
It’s far from trivial to decide whether some program is a better driver than the average human driver if the program gets the newer bigger car and can decide to cop out in cases where we do not expect humans to do so.
Edit: and even within highway miles, autopilot will be enabled more in the "easy" stretches and turned off in roadworks etc.