You sure it isn’t just that they’re more detectable? I mean, you said that you’re going by the language and things like burkas. It could just be that you’re noticing them more than other groups because it’s easier to notice them.
Like, if you came to my town, you might ask, “why does this shithole attract koreans?” It doesn’t in particular, they just stand out against the crowd more than the crackers, latinos and black folks.