There are also countries that are much richer than the US, yet they still have stronger worker protections. Unless the US is some sort of Goldilocks country, with just the right combination of development and size, then there's no reason why it can't have things like nationally mandated paid time off.
Luxembourg, Norway and Switzerland have substantially higher GDP/capita than the US.
As for median income, I think you're looking at income net of taxes, because I'm fairly certain that median gross income is higher in Luxembourg and Norway (and in Switzerland) than in the US. If you're looking at net income, you also have to factor in what those taxes do to improve quality of life (a huge amount, if we're talking about the three countries I mention above).
Idk, I get 6 weeks of PTO a year and I make a hell of a lot more money than Europeans do.
Just because the mandated minimum PTO is 0 doesn't mean everyone has 0 days PTO. Minimum wage is another example - the federal minimum wage is really low but the median income in America is higher than in Europe.
We just don't have the same approach to government regulations.
Making rules at the right level that makes sense is not "oppression". Is it oppressive that you local city council manages rubbish collection and not your national government? Is it oppressive that you have a national military and not an EU military?
The US constitution doesn't give the federal government authority to do this, and rightly so.