Not the other way around? My experience is that the US uses 1-based indexing for floors in buildings and that Western Europe uses 0-based indexing for floors in buildings.
Corrections welcome, but I think Europeans don’t count floors, they count additional storeys, 1-based.
I think that’s influenced from French, which has parterre (“on the ground”) for the ground floor, and étage, derived from Latin stare, “to stand”, for higher (and lower) storeys (in the end, both may come from Latin)
If Europeans use 0-based counting for floors, I would expect at least some language to say “zeroth floor”. I’m not aware of any.
> If Europeans use 0-based counting for floors, I would expect at least some language to say “zeroth floor”. I’m not aware of any.
I feel that argument does not hold water. Nobody says “second month” or “month two” in English, everyone says “February”. So it sometimes happens that a number is assigned to something, but nobody uses the number in regular speech.
I feel that the ground floor is similar: it's got a number assigned to it, but everybody uses a different word, instead (parterre in French, Erdgeschoss in German, ...).
In Germany at least, it is common to find negative floor numbers, denoting floors that are below ground. For example, an elevator might have these buttons (top to bottom):
6, 5, 4, 3, 2, 1, 0, -1, -2
But it is also common to find some other letters on the buttons, instead of the numbers. E.g.:
P2, P1, 4, 3, 2, 1, E, U1, U2
P2 and P1 would be the car park, E would be Erdgeschoss = parterre = ground floor, U1 and U2 would be “underground” (below ground).
I think that’s influenced from French, which has parterre (“on the ground”) for the ground floor, and étage, derived from Latin stare, “to stand”, for higher (and lower) storeys (in the end, both may come from Latin)
If Europeans use 0-based counting for floors, I would expect at least some language to say “zeroth floor”. I’m not aware of any.