What does the ranking look like if you compare percentiles? Naively I would assume as a non-American that if you're in the top 20% by income in the US you end up much better off than the top 20% income Brit, for example. Or is it just actually worse for everyone? It feels intuitively obvious that the average will be worse because, well, the average person is skint and the US is less socialist.
The US health care system is partly socialized. Health care is provided for the unemployed or low income and the employed are covered as employers are required to provide health coverage. The odd ones out are typically small business owners who don't insure themselves and choose to take on the risk of potentially large medical bills. In all cases treatment is required by law, regardless of payment.
Many employers do not provide coverage. They skirt the law by employing people part-time (Walmart, Amazon) or as gig workers.
Even if the law reads as you claim that doesn’t mean you can get care in the US.