I mean isn't one factor that healthcare simply costs more in the USA in the first place?
I've heard that a big part of this cost is due to the highly litigious culture in America that requires doctors to carry very high malpractice insurance, which they must then pass on in their patient costs. Americans love to sue, and this drives prices up.
I don't know if this is true, but its the one argument I've heard over the years that makes the most sense to me.
I once had a worldwide health insurance plan while living in Asia, and it covered all countries EXCEPT the USA, because of the absurd costs there.
And unfortunately, many serious conditions are dramatically more expensive, and potentially more lethal, when presenting late. It's a nasty piece of positive cost feedback inherent to the current US system, and one that disproportionately affects patients from lower income brackets.
Other reasons include the massive costs of running and staffing the billing infrastructure, cost of compliance & provider insurance, and uncontrolled drug pricing.
These factors are not present in most other first-world healthcare systems, or are present but minimised by effective regulation.