Not to be facisious but maybe that’s partly because America has no class-system like Britain has had since the dark ages. Nor does any American have (or truly understand) the ingrained sense of submission to the Monarchy. The Middletons know their place and the degree of decorum that’s required. It’s not about being polite, it’s about being “proper”.
While I get your perception & understanding of the class-system, as you are part of one of the British Commomwealths, and since, probably grade school, you were taught the class-systems, I'm not talking of that kind of class. I'm talking about the kind of "class" in which a person has eloquence, grace of demeanor and integrity. I've seen people here, raised from ghettos & the projects have more "class" that people who grew up with silver spoons in their mouths and went to Yale & Harvard.
It's the class that Amy Tan, a Chinese American author, telling tales & lessons her mother taught her, in her book & movie,
The Joy Luck Club, says, "One cannot be taught class. One has to be born with it."
Even George Bernard Shaw's
Pygmalion &
My Fair Lady, is about how much "class" can one really teach someone?
However, if we go by your definition of class-system & learning one's proper place & decorum, we do have hierarchies within certain types of professions as well as the government. Thomas Markle was a lighting designer. Certainly he knew his position within the TV & film industry he was a part of. He probably started off as a lighting crew member and worked his way up to being an assistant lighting designer, then lighting designer. Yet, he knew his position was underneath the technical director, who is under the director, who is under the producer, etc. I assume he knew his place within that structure.
He probably had also signed non-disclosure agreements for shows he worked on. So that he wouldn't leak any spoilers to TV shows & movies he worked on. Or generally knew to keep his mouth shut about such things.
Yet, for some reason, he can't keep his mouth shut when it comes to his daughter's and SIL's privacy? Nope, I don't buy it. I can't believe she didn't have a conversation with him along the lines of, "Dad please don't say anything publicly that goes on between us, or with you and Harry. Whatever happens has to remain private."
Right after his alleged heart operation, he had an interview with TMZ and, saying he wanted privacy and to be left alone. He also publicly told his other two children to shut up, stop talking about Meghan and leave her alone. So he obviously knows what's the "right" thing to do.
Yet, several weeks later, when The Sun, waves money at him, he's doing a full 180 degrees against what he said he, himself would be doing regarding Meghan.