I think the only country i've been which does not do this is the US. It was pretty weird at first

There’s some confusion here about the exact word being used. The German word that is mistranslated here as “floor” is “Stock”, which actually means “addition”. So the floor above the ground floor is the first addition, not the “first floor”.

Not german here, this is standard and I'm a bit confused by your comment.

0 is ground floor.