1. Yeah that's a good example when it could happen. I expect that is rare enough that it would reasonably fall to insurance rather than regulation. We simply can't regulate every small chance event that could impact others.

2. Victimless here matters in context of regulation. It seems reasonable to consider someone emotionally harmed is a victim, though its important to decide whether emotional harm felt by one is a direct action caused by the other. For example, if someone emotionally responds to seeing my dead body I didn't directly force that reaction on them and I wouldn't say there is direct responsibility for it.

3. We aren't talking about the act of wearing seat belts, everyone should choose to because it is easy. We're talking about regulation and government authority. Regulating sugary drinks, for example, would almost certainly be more impactful.

4. Brakes aren't the problem if the vehicle stopped quickly enough to make me a projectile.

And to be clear, I to wear a seat belt and want everyone to choose to. I just don't want a government to have the authority to require it and fine us if we don't do it.