Right but the biggest country in the EU isn't ~330 million people from about a half-dozen fairly distinct cultures. Remember that the US has cultural representation from many European countries and also quite a few non-European countries.

I'm not suggesting that Italy or Greece or Germany are actually homogeneous culturally but with smaller populations and significantly less immigration than the US I suspect that the variances are smaller and perhaps more surmountable.

Germany's population (83 million) is only about 1/4 of the US and as you go down the list the countries only get smaller.