@SerendipityJane laughing about your friend. Yes I had problems in a public sector employer when they started insisting on ethnic diversity questionnaires which don't work very well for me. And everyone putting flags up, that sort of thing.
I spoke to my grandad about whether he would mind what I put down and he was astounded: "why on Earth are they asking you about that?" Like they were surveying everyone on sock colour, and then started lecturing me on the unimportance of skin colour...
Relates to @Kucinghitam point. My grandad was part of a very early wave of immigration in 1948 and my wider white family lived in the same town and knew one another. We've been fortunate that there wasn't really any racism experienced, minor stereotypes really.
I agree about not thinking about anyone's background unless it's relevant. Trouble is we get TRAs popping up claiming everyone who who supports same sex spaces is white and racist. I might put UK BAME GC women list together.
It does relate to perception of sex. It's shocking how the same family member can be seen as white British, Indian or mixed (all three!) depending on the observer. Trans "passing" as a criteria for accessing spaces just doesn't work.