[jmorphy88]

> I suppose I don't consider the ex-citizens of one of the European royally rules countries to be the same, but there's surely some unifying traits like Christianity.

I don't either, but you did say "Caucasian-looking"...

A mass migration from any foreign culture (that is, highly different from the host culture) would be treated with alarm by the locals anywhere, in any country. It's not a phenomenon specific to the US. The US just happens to provide a particular historical instance of it. Vancouver seems to be providing us another.