I lean pretty libertarian, but even I can acknowledge the societal value of seatbelt laws.
I am pretty libertarian too, but how do you decide where to draw the line?
Should candles and space heaters be outlawed? Start a lot of fires.
Eliminate car radios? Distracted driving is bad.
Mandatory non-slip bathtubs? Lots of people die in falls
Ban swimming in rivers and lakes? Ban home pools? Lots of drownings...
Humans are not good at evaluating risks in general (e.g. fear of flying while driving is much less safe). And when is it wrong to limit one person's freedom in any way, even if it does benefit society in some way? Does it have to be a major societal impact, or is just any positive impact sufficient? It's obviously a philosophical question, but also a very practical one. And reasonable people may disagree on the answers.
There has been a SLIGHT amount of discussion around this concept in the Covid threads lol.
FWIW I am ok with the seatbelt law, and would not cry if Iowa passed a helmet law. My gf would not be happy about that, but she would wear one.