> Every injury or death makes health care more expensive for everyone, even in a place like the US that don't have socialized health care. The costs of these emergencies are largely borne by health and car insurance companies, and those costs mean everyone's premiums are going to be just a little bit higher.

Insurance is a bet between you and the insurance company. If you decide to engage in extra risky behaviour, then a competent insurance company will charge you extra. (Or rather, more PR friendly but equivalent: your insurance company will offer you a discount, if you can prove that you are exercising, don't smoke and always wear a seatbelt, etc.)

Realised average accident rates for certain parts of the population can help you fine tune your risk models, but they aren't mathematically required.

That's why insurance companies can profitably insure one-off events just fine. Eg have a look at https://en.wikipedia.org/wiki/Prize_indemnity_insurance for example where you can get bespoke insurance for your one-off novelty promotion. Golf course A making their golf holes wider won't affect the hole-in-one insurance premium that Golf course B has to pay.

Of course, that's all unless there's some regulation that forces insurance companies to set premiums a certain way. But then, blame that price control regulation.

An insurance company that prices risks accurately will outcompete an insurance company that solely relies on population averages. The latter will overcharge less risky people who drive with a seatbelt on (so they will move to the competition), and will undercharge risky people without seatbelts, and thus lose money on them.

> Also consider the effects on family (or friends) when someone dies (or is much more severely injured) because they weren't wearing seat belts. Maybe the breadwinning spouse dies or becomes disabled, and now the remaining family has to go on welfare. Maybe it was a single parent who died, and the kids end up in the foster system. In the disability case, insurance (which might be Medicare) companies will have to pay for rehabilitation and possibly care for the rest of the person's life. Hell, just the emotional anguish of a loved one dying in a situation where it was easily preventable is an externality worth trying to eliminate.

You are proving too much here. Yes, this argument could apply to driving without a seat belt. But it could apply just as much to any driving at all. Or to lazing on the couch instead of exercising, or to living in the New Mexico instead of Maine, or to drinking or smoking, or working as a lumberjack.

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Just to be clear, on the object level I'm ok with smoking bans (instead of just high taxes) and laws requiring seatbelts. But that's just because they are convenient for me. They aren't properly justified.

Congress fights to keep AM radio in cars