In my school, the Chinese students grouped together, and the Vietnamese grouped together. They stayed that way nearly exclusively, and picked on each other relentlessly, refusing to speak any language (including English) among each other except for their native language.

So at least with that experience, I'm not sure this is a Western problem. I can't imagine that any white person would try to infiltrate and make friends in either group considering how they were treating each other and being so exclusive to themselves. And the fact that they purposely made sure nobody "outside" the group could understand them.

Not only that, the Asians who didn't hang around in either of these tight-knit groups were labelled something akin to "banana" - white on the inside and yellow on the outside - and taunted for trying hide their Asianness. It all boils down to a solid confirmation that mixing wasn't allowed in any direction.

Friendships are two-way endeavours. I'm not saying everyone self-segregates, and I'm sure that even a lot of people who do actually wish they weren't doing it. But it is so common that I think it is unfair to blame it on Western culture.