And the point of etiquette is to signal conformity and social status.

I had a friend who came from a working class culture where social aspiration was measured by tiny nuances, like whether someone put milk in their tea before or after pouring it.

Outside of that culture these nuances were irrelevant. Middle and upper class people had a completely different set of etiquette markers - as well as more or less obvious displays of wealth - which the working class aspirers were oblivious to.