[zmmmmm]

I wonder how many of the conclusions would change if the EU is considered as a "country"?

Which is to say, it's a little bit of a definitional problem around what the word "country" actually means. The US, being a federalist collection of semi-autonomous states is sort of a hybrid country. There are some clear aspects (a single military, federal laws, a common currency, a commonly elected president). But then there are other aspects such as that the autonomy given to states is such that they invent local laws to the extent that for a huge range of areas you effectively have to deal with the US on a state-by-state basis.

[ncmncm]

Historians distinguish "nation", "state", and "country". The US is a State, but not a nation, and not a country. EU approaches the status of a State, but also neither of the others.