What we consider correct or proper English has long been bound up in class distinctions. Prior to the advent of public education, this was much more obvious than it is now. Proper English defined itself as the English used by proper people. “Real” English was the English of aristocrats, thus the phrase “The Queen's English,” which is still with us today.
But even in the supposedly classless or at least socially mobile U.S., we tend to attribute correctness to the social “winners”: educated, urban, northerners, preferably those from “old money.”