If you don't wear a seatbelt, it could kill me when your body is launched out through the windshield and enters my car. On top of that, my taxes would have to bear the direct and indirect societal costs of the deaths prevented by seatbelts (roughly 15,000 per year). Mandating an extra four seconds per person per drive to fasten and unfasten seatbelts seems extremely reasonable, if not morally imperative, to me given those factors.