Semiconductor plants often shut down over July 4th or Christmas for maintenance. You were compelled to take vacation when that happened or you were on unpaid leave.
In practice, where I worked, most managers generally worked it out informally if you didn't have enough vacation days.
And this is in an industry (auto) that actually has organized labor in the US?
What did the auto unions actually accomplish in the last 3-4 decades?
Survival.
When you are the target of a very well-funded propaganda campaign to delegitimize your very existence, what do you expect?
People in the US are so stupid that they denigrate the very unions that stood in front of guns and bullets in order to get them the 40 hour work week, child labor laws, pensions, and health care to name just a few accomplishments.
It's beginning to turn (see the recent teacher walkouts--most of which are illegal in the eyes of the law, by the way), but it's very slow.