The term "White" has been morphing over the years and means different things in different countries. In the US, "White" now includes people in the Middle East and Northern Africa (such as Arabs, Egyptians, etc), even if they're not perceived as being white.
And because so many people have such different ideas on what "White" means, it can cause issues. Does is mean people with Northern European ancestry? Or is it just about how you look? I've been seeing a lot of people get picked on for being white, when they're, say, from Brazil and just have light skin (what the US calls White Latino). "Passing for white" is just a way for people to judge others without knowing anything about them, which negates the One Drop rule.
People of mixed ancestry have no place anywhere because people expect them to conform to one culture (are you black, Latino/Hispanic, Asian, or white? Can't just pick everything you are, apparently). If someone who happened to get the lighter genes in a mixed parentage (one parent of Northern European ancestry, one parent of a different ancestry) feels closer to their Native American heritage, or African heritage, etc, they *will* get shunned by both sides.
As for "why the white man always singled out"... If the places of power were switched, it would be someone else singled out. No one likes those who are in a social power position, even if that position is far far less powerful than it used to be. They are perceived as an enemy, of sorts, an oppressor of the people, even if it's only a few of them. People like to generalize (oh look, people of this look are in power and have been in power for a while, they're all evil now, even if they are less privileged than most other people - as long as they have white male privilege, they will be judged, even if they're homeless because their wives took everything and they're in need of food and medical care that has been denied them multiple times).
People need something to hate against.
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Your Aspie score: 171 of 200
Your Neurotypical (non-autistic) score: 40 of 200