Black boxes are like photoradar and redlight cameras. They do not have the full story. Foto radar and intersection cameras do act as deterants. They are revenue streams. That is the motivator.
Friend of mine got a red light instersection infraction ticket sent to him in the mail. He had moved into the intersection against the red light to allow an ambulance to pass through. He had to pay the ticket because the photo showed his car - not the ambulance in the intersection.
This is exactly the type of thing that can happen with black boxes. The FULL story will never be known in a post-event snapshot.
There already have been many court cases in Canada both for and against using the data. I watched a news documentary not too long ago as an insurance company tried to use this data to prevent paying in a case where a woman was killed. Insurance companies want to use the data where they can in order to prove reasons that would allow them to avoid paying out more money. Extrapolating the data is not an exact science either - the police in that show admitted it was closer to a lie detector test as it could be misunderstood data.
This is the motivator for getting black boxes installed in personal vehicles.
Open your eyes. How could a black box ever ever help you or I. Would you sleep better at night knowing your new car was so equipped?