Not sure what part of the Western US you live in, but I've lived in Washington, Nevada, California, Arizona, Utah, Wyoming, Colorado, New Mexico, Texas and Idaho, and have never come across the idea that Columbus day is unknown. If you don't hear it mentioned, perhaps the problem is with your auditory senses.
Huh. As a Canadian I am floored that Easter (Good Friday, Easter Sunday, etc.) doesn't figure in there anywhere. Is that... not a holiday in the US? Or is it just one that is typically assigned by the individual states?
It's officially a secular country, so if anything it's a bit weird that Christmas is included. And there's no need to make Easter an official holiday, since it's always on a Sunday when the majority of people aren't working anyway.
Of course, the quiz is about the holidays recognized by the federal government and the official answer should be based on the name used by such, but I still feel that Indigenous People's Day should be accepted as a type-in since that's what that holiday is known as in many parts of the U.S. Of course, most people who try IPD will think to try Columbus as well, so I suppose that it's largely a moot point, but I still fell it would make sense as a type-in.
As a British person it shows the divide of the Atlantic. I have no idea about most of these (except Christmas and New Year). I also knew you had something called Thanksgiving that was something to do with Turkeys.
I find it a bit sad that a lot of the UK official holidays are just nameless bank holidays. Why not take the opportunity to celebrate something, even if only symbolically?
Not a federal worker and I do not get: MLK, Washington's/presidents day, columbus day, Juneteenth or Veterans day off. That's 5 of 11 days (almost 50%) which we'all in the private sector do not get.
When I left the private sector to work for the government, I showed up at work on "holidays" a handful of times before I got used to the fact that we were off/closed not realizing nobody would be there. I still come in and get things done without distractions on these days sometimes.