United Nations are not united obviously. In the same vein European Union is not a union. There is 'we' ('my' country which is more important) and 'them' (the hypothetical 'Union'). So there is conflict and struggle of us against them. People in every particular country cling to their language, it's history and tradition, so also the images of the 'others', of the past issues and grievances. Such an arrangement is not effective and probably not sustainable.

A true union there is simply no division, not x separate countries with separate governments, armies, economies, languages.

No country can exist completely isolated from the rest.