The lower classes' standard of living is all that matters. If you're rich, you can live especially well even in 3rd world countries (where servants are cheap and anything can be paid for).
But household income adjusted to PPP isn't the only quality of life indicator. For the 'median' family in the US, they can expect to pay far more for health care and transportation.
US PPP income is highly skewed because the US dollar is very strong, and a basket of consumer goods in the US is very cheap. Healthcare and education on the other hand are astronomical, and certain items seen elsewhere as 'luxuries' can be required in many parts of the US (one or two cars, for instance).
Anyhow, most quality of life surveys put the US at around 10th, which I think is pretty appropriate based on what I've seen (both statistically and anecdotally).
Income PPP adjusted also doesn't factor in taxes. Things like free tuition are paid for by much higher rates. Healthcare is usually part of compensation packages in America. I'm not sure if that gets included in gross income.
My main problem with quality of life indexes is they tend to overvalue income equality. It's true that income inequality is generally associated with poor countries but the USA is clearly an outlier. Favoring equality is a normative judgement.
Are tax rates really that much higher though? In my state, middle class pays 25% Federal income tax plus 9% state income tax plus 6.2% SSI tax plus 2.9% Medicare tax plus 0.5% transit tax. That's 43.6%.
It's notoriously difficult to calculate effective taxation in the US since it is fragmented across so many jurisdictions (goes hand in hand with the US's incessant attachment to federalism), and because many of the taxes in this cascade can be partly or wholly deducted from superior taxes (e.g. state taxes deducted from federal taxable income).
Nevertheless, you are correct that the aggregate effect is that we pay roughly the same cumulative tax as the average Western European citizen. A little less, to be sure, but we get vanishingly little for it in social benefits, particularly in the catastrophe that is health care. The result is that we have to pay both sides: pay the government, then pay (gargantuan sums!) out of our own pockets for things like tuition and health care.
The world is not a dichotomy. There's a whole load of people between rich and poor who's standard of living can be poor, despite their relative wealth.
My point is that to measure a single country's progress, you need to measure the quality of life for the working class, minorities, retirees, etc...
That's why things like health care, transport infrastructure, PPP, median and average salaries, etc... are all factored in to quality of life rankings. And why the US isn't the best country to live in.
Obviously there's many people between homeless and billionaires, but I was responding to a post that claimed the US' quality of life was better because of the potential to live well.
The term "standard of living" is a pretty fuzzy one. The only way it makes sense is to talk about the minimum standard of living, e.g. say what the standard is for the bottom 20% of income. In this case it's probably not a good indicator for the US. The US is so diverse that "average" standard of living doesn't really mean anything. For a single (rich) state it might, as it does for a small nordic state.
