This sort of technology would be great, even if the data never leaves the user's account, is never farmed by Tesla, and is never used by the autopilot.
Imagine if the parent poster falls asleep at the wheel and does injure or kill someone. They could point to the fact that it's never happened before, but if the court can subpoena Tesla to get data that indicates this guy dozes off with some regularity (and can see indications that he knew about it), then he's going to face a harsher sentence, possibly even bumping it up from involuntary manslaughter to second degree murder if they can argue that it was extremely reckless disregard.
Imagine if the parent poster falls asleep at the wheel and does injure or kill someone. They could point to the fact that it's never happened before, but if the court can subpoena Tesla to get data that indicates this guy dozes off with some regularity (and can see indications that he knew about it), then he's going to face a harsher sentence, possibly even bumping it up from involuntary manslaughter to second degree murder if they can argue that it was extremely reckless disregard.