Yes. For a few reasons, and here they are, in no particular order:
1. America is not composed of a multicultural blanket. It is a melting pot. More than any other country I have been in (and that's a lot), people come to America to leave behind their country/culture/language, and become American. This isn't a criticism, so please don't take it as such. It is merely an observation. USA is a melting pot - everyone is boiled down to Americans. No where else in the world is being able to speak only one language celebrated as nationalistic purity.
b. Nations such as Canada (as one example) have legislated multiculturalism. They celebrate the ethnic origins of immigrants, make street signs in foreign languages, create pockets of foreign culture within larger cities.
iii. While America is large and diverse, it certainly is not the most diverse country in the world. It is impossible for Americans to understand the level of diversity that exists in Europe. Stacking countries on top of each other like that, and then throw in immigrants from elsewhere, is way more diverse than any American city. The down side is that this aspect of multiculturalism also ramps up racism, which is alive and well in Europe.
These are my opinions. Feel free to tell me to shut my cake hole.