You're pretty dismissive of a theory I find interesting, I wonder if you've ever really entertained the idea that a wealthy country will cater its services to those who can pay, leaving those who can't pay behind.
So USA has a high median income, so we have high education outcomes, high healthcare outcomes, right? We certainly have the best schools and the best hospitals. But only the top few percentile can afford the best schools and best hospitals, everyone else gets left behind.
But we have higher infant mortality than many countries with lower incomes, and we don't compete so well when it comes to average assessment scores.
Naturally I was exposed to this thinking via a TED talk years ago, from this guy:
https://www.ted.com/talks/richard_wilkinson
Maybe you want to offer a rebuttal, or maybe you just want to insist he's jealous.