It seems the Germans like duplicate tags since the country address is easy to deduce from the country polygon. It could be justified on edge cases like "near the borders" or outside the polygon but not generalized, I don't know how this community has reached such senseless decision- Probably from some data consumers too lazy to use some complex queries in a spatial db.... Sad that the majority of contributors have now to assume this bad idea. I like how this community is sometimes pushing for more standardisation/consistency like for postcode polygons or speed limits but here I cannot follow. By chance, in my country, we have a general consensus to avoid unnecessary duplicates.