Statistics are always difficult and hard to translate to conclusions, but in the case of autonomous cars it seems like advocates really willing to bend them to the extreme to make a point about how autonomous cars will be safer than humans, even though it's impossible to say anything sensible about that except that 'the average driver' as a goal for safety seems like a very bad target to aim at.
[1] http://arstechnica.com/cars/2016/04/car-makers-cant-drive-th...
That's a good point. It makes sense that the standard we want self-driving cars to achieve is the crash rate on average driving conditions, not the average driving crash rate. The latter is lowered by drunk driving, drugged driving, joyriding and other willfull neglect.