Remember, when one gets behind the wheel and drives to work, school or whereever, he is sharing the public's road with other drivers. While I am one of the first to complain about govt's intrusions into our lives, whether or not one buckles up does affect the other drivers.
A few years back, a woman lost control of her car and was ejected from her car, over the guardrail onto the freeway below. The investigation that immediatly followed closed the freeway for hours. Fortunately, no one else was hurt, but many were inconvenienced and with the traffic tie-ups that ensued the possibility for subsequent traffic accidents increased greatly. This is definitely a case where a driver's non-use of a belt risked the lives of others.
Good God. EVERYTHING affects everyone else. So we should have rules for every nit-picking thing. Correct? I guess so.
By your example - why even drive? It wasn't just her body that affected things - it was her car! So we should ban cars.
Sorry, but I can't buy that.
If the initial impact was so bad to eject her because she didn't have a belt on, the impact was also bad enough to knock her out or at least render her unable to control the car anyway.