The following categories of people have much or all of their healthcare expenses covered by the government:
1) Military (and their families)
2) Retired military.
3) Government workers (all levels of government—not all paid out of the federal budget, but paid by public dollars nonetheless; this includes teachers. To be clear, these folks all pay quite a bit themselves, too, but their insurance is covered by the taxpayers. This isn’t a complaint, just an observation)
4) Many of the very poor (Medicaid, CHIPS)
5) The old (Medicare)
6) The disabled (Also Medicare)
7) Elected officials.
Probably a few more groups I’m forgetting about.
This ends up being a large proportion of all people in the US.
On top of this, the government funds things like healthcare research.
End result, our government spends as much per capita as some OECD states do to provide universal healthcare… but we spend that much and don’t cover everyone.
Part of the reason the math works the way it does is that the government covers a lot of the costs for some of the most-expensive groups of people (old, disabled, veterans with extra wear n tear if not outright injuries).
