The same applies to most former continental Europeans colonies in latin america and africa. 0 based indexing, sometimes with Floor 0 (argentina comes to mind) or simply ground (Terreo in Brazil)

Except people call it the "ground" floor which makes sense, not the "zero" floor which does not.

It’s not consistent but I would estimate that “0” buttons are as common as “G” buttons in elevators in Europe - along with -1, -2, etc for basement levels.

0 makes sense when you consider -1 to be the first basement level.

Which also gently introduces children to negative numbers : - )