I understand suspension of disbelief, so you don't need invite me to try it like you're talking a kid about broccoli.

Haha, ok, I wasn't trying to be patronising - my suggestion was that you try suspending you disbelief in situations where you otherwise might not. Clearly you know what it is, I didn't mean to suggest otherwise. Jumping ahead a bit to another relevant part of your comment...

Suspension of disbelief only has meaning for an audience that already has knowledge of the material

Where I am suggesting you might suspend your disbelief is exactly that - a situation where you have knowledge that the world you're seeing is inaccurate. Anyway, I don't mean to come across as condescending, sorry about that.

Casting directors do not cast "blind" except background crowds, and even then the overall look and feel is as important as paint scheme and set decoration.

Blind casting doesn't mean you have to have no artistic vision. It just means you aren't concerned with, for example, the gender or race of the actor. I saw a production of the Little Prince a while ago where the titular prince was played by a woman. Now, given the storyline (which was presented more or less true to the book) I think it's clear that there was no philosophical motivation behind the casting... She was just small. I'm sure it was a conscious decision to cast someone small, but do you really think they specifically wanted a woman? I doubt it.

I'm talking about serious stories where everything seems to be meticulously recreated except the painful elements of society are being whitewashed for the sake of pleasing modern-day sensibilities

This specific situation I can understand. The reason I was inclined to argue with your original point, and why I jumped to Bridgerton as an example, is that I have usually seen these arguments presented in relation to things just like Bridgerton, where they really have no place... So, do you have an example?

I'd also ask, given your example, what your perspective is on modern Cowboy films still presenting the old west as predominantly white?