And my favorite -- you need to go north from Miami to be in "the South"

These American peculiarities are funny too, but they are mostly historical, and from that perspective have reasonable explanation. In turn "we are not Eastern, but Central" is relatively recent PR-born madness. Somebody decided that EE often associates with questionable things like alcohol consumption somehow, so the solution is to separate yourself from other drinkers by claiming being completely different "Central" kind. Nobody stops drinking meanwhile, because why would you? I simplify the story, of course, but the logic is exactly like that.