I imagine OP says its a tendency in the West as to avoid generalizations outside their personal experience, not because it's necessarily not the case outside the West. Anecdotally, I think there's at least some distinction between white people in Asia. For instance, there seems to be a distinction from white Americans from white Europeans.
That said, I don't think the claim quite holds that westerners view all minorities as the same. East Asians, while maybe initially assumed to be Chinese or Japanese, have generally unique stereotypes in the US. I also recall a story reported in This American Life[1] that describes a black American woman in Paris, and how her treatment depends on whether she's seen as an African or an American. I think it's perhaps a bit more accurate to say that the broad appearance of a minority group invokes certain stereotypes, but these stereotypes will become more specific with more information about the individual. There's obviously a limit to this, since a Chinese person from Shanghai and a Chinese person from some small city in Henan is a distinction that probably won't mean much to most non-Chinese, but I think people would realize there _is_ a difference, just not know where that difference manifests itself, and obviously cannot change their mental models without that knowledge.
I’m not sure if this is a legitimate question or an attempt to make some sort of “but also not-the-West is bad!” point; if the latter, this is a comment on an article about caste discrimination in California, which is probably why the its observation focuses on the West, instead of talking about parallels in other cultures.
Is unique to the West? Do people in Asia distinguish one European from another? How about in Africa?