Well, I do get upset and I do care. I am sorry if some think that we legislate too many things. Meg, you summed up my opinion, perfectly. I'm not a nurse, but sure, don't wear your helmet or your seatbelt. When you crash, and you will, "we" will be paying for it. Especially if you don't have health insurance. My state has a new mandatory health insurance law. It is reasonably priced and covers a lot of stuff (my son has it). People complain about that, too.
I went through a car windshield when I was 15. I have not been in a car without wearing a seatbelt since then. And in 1969, I don't think anyone else wore one.
One time, I said something to a a young teenaged couple who were holding their baby on their lap, no car seat. They got enraged and tried to follow me. I just drove home and they gave up.
Until people think about the consequences of not following safety rules, I will keep saying stuff to them.