manners in my mother’s sense were but etiquette and that in turn etiquette was but a code by which the elite distinguished itself from hoi polloi in order to maintain its economic and cultural dominance
Actually it's the middle class which traditionally had the best manners. The upper class was often just as rude and vulgar as the lower class.
The decline of manners is a symptom of the increasing selfishness and lack of respect for others evident in society.
"The upper class was often just as rude and vulgar as the lower class."
Oh I don't know. I was raised in the south (Nashville) and most everyone was polite. The reason? You might get one upside the head, or worse, if you were rude, especially to a woman. I don't think that's true now though after forty years of Marxist conditioning.
Some young people now don't think there are any consequences for their actions and they can say or do anything that strikes their fancy. Wonder where they got that idea.