How would that even work?
This works through a mechanism called a "terror watch list"
For example, imagine you're a Youtuber and you make a serious, fair film about the Israel-Palestine conflict. You successfully get access to senior people on both sides.
Except Hamas is a terrorist organisation, and to get that access you've visited online forums about the organisation, contacted people in the US associated with it, and flown to a terrorism hotspot to meet with terrorist leaders. That pattern is pretty similar to someone who had been radicalised and wanted to fight abroad!
So you're put on a terror watch list, and at the border you're subject to extra searches, with the random delays that entails.