That's not strictly true. In the US there is in most states NO requirements for paid leave outside of a few protected types. But not vacation or sick. And we also are largely not unionized. We still have time off albeit MUCH less than Europeans and such.
Though I'd argue the norm of having any paid time off is a byproduct of labor/union battles in the past.
We're given just enough scraps to avoid mass unionization. That's because the last time it happened we got The New Deal. This time it'll be the Economic Bill of Rights. The leftist platform hasn't changed for 80 years.
Would be nice if there were more voices calling for democracy in the workplace. That would change so many things and make concentration of wealth and political corruption much more difficult.
I dunno. I work a 35 hr week with 6 weeks paid vacation and 20 days paid personal leave each year... Oh, yeah, and it accumulates annually if I don't use any of it.
Oh, and 17%>of my income is paid into retirement in addition to my salary, not out of my salary.
It's a bit above the legal minimum, but it's still pretty normal here.
I'd say you earned them as part of the agreed compensation in exchange for your work. That way you also cover circumstances where there's no union, and no government requirement, but the employer still offers PTO to be competitive with other employers. Which theoretically could also be driven by other people's unions or governments, but then that would be indirect.
Besides which, regardless of how the arrangement came to be, you earned your PTO.