Cranford High School seniors in the 60s had a tradition of skipping school on a certain day in June every year. On that day classrooms were lonely places for those whose parents forbade them to participate in the annual final act of defiance and celebration before going on to the "real" world.
I was one of those abandoned by her classmates as they went to the lake or to the city or somewhere to sow some wild oats.
I am not sure what made my less-than-model parents take a stand about skipping school, but they did. My guess is they understood the importance of valuing an education; or maybe they were just trying to torture me. Either way, the penalty was severe. If I dared to miss school that day, I would not be allowed to go to my senior prom.
Today I went to a local elementary school where I read to students once a week only to find that to be a lonely place, too. Half of the class was missing. Why?
Their parents kept them home.

Why?
Carnival.
Today is a school day.
"Oh, they don’t do anything anyway," is what I was told parents nowadays believe about school days adjacent to holidays.
So, if "they" don’t do anything on those days that "they" are getting paid for why aren’t parents raising hell about that, instead of supporting it by allowing children to ignore the rules.
If parents continue to ignore the real needs of their children by minimizing the importance of getting an education, or just the importance of showing up, we are all in trouble – and for a very long time.