[bazzargh]

https://en.wikipedia.org/wiki/Annual_leave#Leave "Most countries have labour laws that mandate employers give a certain number of paid time-off days per year to workers." (it goes on to point out that the USA - with the exception of Maine and Nevada - is the outlier in western industrial nations in not having this)

The "right" is also in the Universal Declaration of Human Rights and International Covenant on Economic, Social and Cultural Rights; see https://en.wikipedia.org/wiki/Right_to_rest_and_leisure

Ironically, a lot of this dates back to the Haymarket Riot in Chicago in May 1886 (over the eight-hour-day movement), which led to May Day being a worker's holiday in much of the world...but US politics meant they got an alternative holiday in September.

As RedCondor points out, "who pays for it" has it backwards, companies gain value from the work of their employees, so effectively it is just giving back some of what they "pay" the company in labour.