Because Americans are mainly "rootless" people who for some reason have this inferiority complex towards Europe, even though the American "culture" influence is basically the status-quo of the western world.

In Latin America that didn't really happened because people took Native, European and African culture aspects and made it their own "thing". Which is why you don't see as many "we wuz europipo 'n shiet" like they do in the US.
Not saying these don't exist, but these people are usually made fun of and most of the time they aren't even "100% Italians".