In some respects, the ideal world is one in which everyone’s premiums are tied to a free and easy Apple Watch-like device that silently tracks exercise, blood sugar at a frequency that can tell when you ate a big dessert, air quality (and the presence of smoke or pollution), blood alcohol content, whether you are in speeding cars, whether you are participating in dangerous sports, etc. Such a system would directly confront individuals with the cost of their behaviors in an economic way, probably leading many or even most people to improve their habits in the aggregate.

But such a system comes at other costs that most people intuitively feel infringes on core values they have.

Edit to add: this system would actually have some great advantages over an “existing conditions” tax in that now you pay low rates until you have diabetes, all during the time you are leading the unhealthy lifestyle. But once you have it you are not rewarded for starting to exercise and eat healthy and get it under control. In the hypothetical scenario above, you’d be punished economically during the period you were building bad habits and you would be able to restore sane costs after course correction

There's a similar phenomenon when people grouse about paying taxes for "roads I don't even use." Even if we assume zero indirect benefits, the billing infrastructure necessary to truly achieve that goal would create a creepy panopticon of constant surveillance.

This is difficult to convey to certain brands of self-styled libertarians.