Often, the problem goes even deeper than grammar. White people often judge Black people negatively just based on their patterns of speech — their accents in other words.
Linguists see this sort of phenomenon often in languages besides English, and they refer to high-prestige and low-prestige dialects. It’s all invented, of course, which linguists realize. When they say high prestige, they’re referring to a group of people who feel they are superior to other groups of people and that their dialect is therefore also superior.
It’s not a nice thing. All languages change all the time, as patterns of speaking and accents change all the time. There’s nothing wrong with that, and no particular style of speaking is any better than any other style. Obviously.
Judging Black people negatively because of how they speak is pure racism.
I don’t know if you saw this article, but I wrote recently about a Black CBS news reporter who had to put up with all kinds of racist bullshit from his bosses because they perceived him as sounding Black (and gay) on the air.
