I'd love to see this argument used to get rid of legal authority to create building codes. You make a great point, and you're effectively pointing to the fact that, at least for that specific problem, the market is much more efficient and solving the problem than government regulations.

The car seats one is tough. If you've seen first hand examples of people actively choosing to forgo car seats, I'm not sure if that's a problem governments should solve. Unless the state directly claims "ownership" as it were in the child, the parent is their legal guardian and if the parent makes a terrible choice they have to live with the repercussions. We don't regulate all decisions that can harm a child, that's a tough line to draw.