I've managed thousands of people. In my experience people didn't feel guilt about taking PTO, they felt FOMO because they didn't feel secure in their position or at the company. They felt something would come up or someone would undermine them while they were away that would affect their employment.

I think there's some "grudging acceptance" from managers. "Oh, you're going on vacation on those days. Um... well, we'll still try to get stuff done without you..." And so you feel guilty for going on vacation.

Whether that is deliberate strategy may vary from manager to manager...

In my experience there are several ways to look at it. One is the very basic unspoken rule that many feel that you taking time off puts your work on someone else's shoulders, so don't do that. I have also heard the phrase: If we can survive without you for X days, we can survive without you. So taking a proper vacation is not felt to be attainable. Then there is the whole, I gotta get ahead in my work to prevent the feeling of being a burden to others and catching up on voicemails and emails during the trip and then spending the long hours once back to catch up to all the things you missed etc.