Because the things that determine your auto premiums are for the most part fully public activities. You are out there driving around where you can get in wrecks and get citations. You personal behavior that affects your health is mostly private behavior. The level of surveillance necessary to detect unhealthy lifestyles would be the most intrusive imaginable.
Never mind that the usual norms of “acceptable” healthy behavior are largely crap. Remember.. “Don’t eat butter, eat margarine”.... 30 years later.....”Hey wait, don’t eat margarine eat butter!”
So, Doc, keep your filthy medical imperialism to yourself.
Sure. But, one doesn’t need car insurance, if say you use your car on only on your private property.