>>28504297
Probably the same reason Americans don't mention their state if that is not relevant to the contents of their post.

There's another reason that just came to my mind: your average American doesn't know where most of the Euro countries are, but West/Central/East/Balkan/Mediterranean gives the reader rough estimation of what to expect in terms of weather, culture, prosperity and so on. Same reason state names don't mean much to Euros, most of us probably don't even know where the salt states are.