Your larger issue of mandating safety vs personal freedom loses traction for me when the injured party then turns to the govt for care (which happens a TON). At that point taxpayers are paying for his/her poor safety decisions. And we dont have the stomach as a society to simply allow injured people to suffer and/or die.
This is the most interesting aspect of the seat belt debate, if you ask me. I agree that if you're wearing a seat belt during an accident, you have a much greater chance of avoiding serious injury or death. However, I don't agree that on a societal level, enforcement results in fewer car-related fatalities, or less burden on the welfare state.
While seat belts help individuals survive accidents, drivers engage in riskier behavior when they feel safe. There's an interesting article on this subject:
https://content.time.com/time/nation/article/0,8599,1564465,00.html
Arguments for authority usually appeal to some sort of "greater good", where presumably a more authoritarian society will result in less harm. We're told that it's in our mutual interest to forfeit our liberty. I disagree. When we forfeit our freedom in exchange for safety and protection, people also tend to shirk their sense of personal responsibility. We become both reckless and indifferent. Statistically, this might actually increase car related fatalities.
I think it's a good analogy for authoritarianism in general. Live in a country where the state has an acute monopoly over the use of violence, like in Canada, and people will stand there with their cell phones, recording your suffering while waiting for the police to arrive when you're being assaulted. I've seen this sort of thing in Toronto, Vancouver and Montreal, where over a dozen people waiting for the bus will stand there, watching an assault take place. They have no sense of responsibility. When you try to convince people to help you intervene, they're reluctant. That's not a community. It's a clustered group of indifferent individuals, weaving through one another like cars speeding down a highway.
I'm not an idealist, but I'd feel safer living in a community that emphasized freedom and personal responsibility, than a risk-averse society that is heavily policed.