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.
0 makes sense when you consider -1 to be the first basement level.
Which also gently introduces children to negative numbers : - )
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.