Fanta, Sprite, 7-Up are all brands of Limonade. (I suppose technically Coke, Pepsi and other colas are too, but they're usually named "Cola" generically.)

Yeah, sure, I assume Germany -- like every other country -- also has / had the precursor mix-it-from-scratch version, but at a guess only grannies who make it for more or less appreciative grandchildren use the word in that sense any more.

The word itself, with its "-ade" ending, looks French, so to be fair, I'd say it's the French, not USAmericans, who get to define what it means globally. Dunno for sure, but I'd guess they're with Germany, Australia, and the rest of the world. So, no, Drew: It's America, not the rest of the world, that doesn't know what lemonade is. HTH with your cultural superiority / blithe assumption complex.