You'd be surprised at how very accurate it is. ALL employers have the legal right to dictate when a person takes their vacation time, and I think it's happening with increasing frequency. Where we live, in a fairly industrial area, they have designated shut down times, and that's that - THAT is your vacation. Around here, shut down is typically the two weeks of Christmas or two weeks in the summer. Too bad, so sad if you don't like it. So you have those people.
Then as you said there's the seasonal workers.
Then you have the places where vacation slots are chosen based on various methods - seniority, first come first serve, a pool, etc... So, you're left with what you get.
Then there's anyone that works in the school system (public, private, college, university etc), plus families who have children in upper grades where taking them out for a week or two is either a) not allowed or b) too disruptive to their education, or even families that just aren't allowed vacation in any grade as an excused absence. That is a huge number right there, considering in the US alone, there's roughly 3,000,000 K-12 teachers, and over 17,000,000 high school students.
And of course, then there's the college and university students themselves.
