But this way they can't tell how many accidents the hands-off autopilot could have caused. Number of accidents avoided alone is not enough to say this technology would decrease the number of accidents.
That is only partially true. They can resimulate what the automation _would_ have done given all the telemetry and video data leading up to the event.
This is why "partial automation" for the initial data collection still produces valid results. You can replay data against updated models and do "what if" testing without actually sending the car back out on the road again.
This is why "partial automation" for the initial data collection still produces valid results. You can replay data against updated models and do "what if" testing without actually sending the car back out on the road again.