It varies wildly, but it helps to realize that Americans don’t really think about annual leave in the same way as Brits. Leave might be PTO (paid time off), personal days, floating holidays, or other random days off. In many places you also get a set number of sick days which roll over, so if you stay somewhere a long time you might end up with over 100 days to take off, that the company has to pay out to you if you leave.
This is one of the reasons many companies are switching to unlimited PTO. Mine has been considering it.
The job I recently applied for had 25 days PTO, 10 personal days, Fridays off in summer, short hour Fridays the rest of the year, some sick days (I don’t remember how many), and all the public holidays.
There’s FMLA at a federal level, which is unpaid, but often better leave at a state level. In some states they have paid sick leave, paid family leave, and other random leave. There’s also military family leave, caregivers leave…
If you are sick you start on sick days which tide you over on full pay but then potentially you go into Short Term Disability then Long Term Disability, which are both paid out of insurance policies they might or might not be provided through your employer.
You really can’t just compare US leave policies to UK policies. It’s not apples to apples.
(Can you tell I work in HR?)