this is why the legend in this map is misleading.

eg, in hungary's case, you'd never have this kind of confusion about the first floor, because of the words used.

• ground floor = földszint (literally, ground level)
• first floor = első emelet (literally, first thing that is raised, emel is the verb for lifting, raising)

so you start building a house by building walls around the ground floor, then you raise a story on top, which is the first lifted thing (that is, it's not on the ground).

so there's no programmer's logic involved, it flows quite naturally from the words we use.