> If you have accrued vacation, you "earned" your vacation and they can't take it away from you without compensation... If they fire you, they should even have to pay you your salary for those vacation days.

This is indeed the law in Israel. What happens is that people are allowed to accrue a number of vacation days up to a limit, typically however many days of vacation you earn in a year, times two. Then the company forces you to take, at the end of the year, a number of vacation days down to the limit.

Companies where this limit wasn't put in place introduced a moral hazard, whereby people would wink-and-handshake with their superiors when they would take a reasonable amount of vacation without actually reporting the vacation days to HR, wherein HR didn't really have the means to detect and enforce against the fraud. Thus people would work for decades, retire, and take compensation for decades of "untaken" vacation days, on top of the normal retirement packages. These policies represented usually $1+ million in obligation per worker and thus were clearly unsustainable without some kind of enforceable limit.