> Given that the US has a population of 342.7 million people [3], we could have single payer healthcare for every resident without raising taxes if it cost less than $5800 per person per year. The UK's universal healthcare system costs ~$4700 per person per year (~£3,500)[4].
Except we couldn't. For the same reason our public schools can't get Finland's test scores while spending $3,000 less per student pear year than the U.S. For the same reason our public transit systems can't build subways for $100 million per km, like Spain.
If your implication is that this is a private vs public spending problem, that's not it. Healthcare in the US (both private and public) costs dramatically more than in other developed countries.
Why that is is a bit complicated and doesn't have a single root cause. It's also a bit tricky because every major component blames the other components for the total cost.
Part of the problem (roughly 10% by one estimation I read) is drug prices. Drug prices in the US are >2x the price as compared to other developed countries [1].
[1] https://www.ncbi.nlm.nih.gov/books/NBK611301/