This probably used to be way more common, like when skyscrapers first became a thing, but I'm an American and was recently in an elevator that had the 13th floor button. It's definitely not a universal truth or like a building code violation or anything
Might be a fake 13. They’ll have a button for 13 in the elevator, but 14 actually gives you 13, 15 gives you 14, etc. That way nobody ever thinks they’re on 13, and the fake button convinces them that there is in fact a 13th floor.
Or 13 is a mechanical floor.