If I hit your car and you die, then it's my problem, regardless whether or not I'm at fault.
Yeah, I guess it is. And if a meteor hits you on the head, it's also your problem. I'm not sure why people persist in believing that the government can legislate all the risk out of life. If you hit my car and I'm wearing a seatbelt, I might still die. So what then? If the accident truly is not your fault, then ideally you would not be held accountable for my death. If you were held accountable, then that's a problem with the legal system, not with my personal choice to wear a seatbelt (or not). You can't fix a flawed system by adding more nonsensical rules.