Yes, exactly. They don’t treat such subjects, that’s why the CC fits into the story without there being bloopers. Let’s take Summer Fever or any other story of Lucas’. Do they treat racial interpersonal relationships in any way with the MC? No. Because the story doesn’t revolve around interpersonal relationships at all, it has a main plot and goal and that’s the point, not the characters backgrounds (to the extent that they don’t influence the story, of course).
If an author wants to reflect on such interpersonal relationships, by all means, they can. It’s their story they can write whatever the hell they want. If they don’t reflect on it, it’s a problem. If they reflect on it, it’s a problem because it might intersect with the CC. If there’s no CC, barely any readers will follow through with the FIRST episode (they won’t even carry on to the next chapter when they see there’s no CC). If there is CC, it might intersect with what the plot. If there’s limited CC, there’s still a whole bunch of people who aren’t willing to play the story. If you tell them at the beginning of the story that it’s important to note that if you don’t keep the MC white/black/whatever they were designed to be originally, it might create discrepancies, then they would still customize the MC to their liking and if not you (because you understand you were warned about it) then others would still come and complain about this issue (I’m not referring to you complaining, but to the people who would still be annoyed by this after the warnings they got).
See? That’s the problem. Though I agree that there should always be disclaimers that the skintone is important or there might be bloopers and things that won’t make any sense.
And all I’m saying is tolerance towards writers is key. You know the MC was supposed to be white before you customized. You very well know that it’s why the MC is not supposed to understand her black stepbrother’s struggles. So why does it get such a reaction out of you that you get annoyed/frustrated? You, as a black reader (I assume), understand his struggles anyway, it doesn’t matter that the MC was supposed not to understand. What I’m saying is this is not something you can’t turn a blind eye to. Just shrug it off, not everybody is a pro coder.
EDIT: How many times I myself played stories where the MC was black (because of limited CC, or because I had full CC but I still made my MC black, even though I’m white) and it didn’t fit somewhere because whatever small little detail. For example I made my MC POC and then the whole family was another color, or vice-versa. That’s something that really annoys me. But I couldn’t care less, I knew I customized the MC because I can turn a blind eye to such mistakes. There are just technicalities.