I think a piece that you're missing here is that health problems get drastically worse, and more expensive to fix, when they're not addressed.

Problems are often not addressed in a reasonable time frame because many people don't have access to reasonable health care. Even they they do, they may be hesitate to use it. Anecdotally, last time I went for a preventative check, I was given an FAQ sheet when I signed in reminding me that if I ask about anything specific, or diagnostic, that is not preventative (as if I'm supposed to understand the difference), then it would have to be billed separately and may-or-may-not be covered by my insurance. That was almost enough for me to not ask my doctor questions while I was at the office.

I would imagine that more widely addressing issues early on before they become expensive would remove another large portion of overall US healthcare costs.