(original topic); I think it's just upbringing and how people speak in certain parts of the country. When referring to the "Black" dialect or accent, I can't help wondering if that's because in the times when Black people started to learn English in the USA's South, the population was mainly French-ancestry, whereas the Northern states were mainly of British ancestry. Only a guess....
I hear radically different accents among people from the East Coast to the Midwest to the Pacific Northwest to the Desert Southwest to Texas to the Deep South. Very distinct differences!
I have a Cali-sylvania accent.... Family from Philadelphia but I was born & raised in Los Angeles. Nobody can figure my accent out, and they often ask where I'm from. Strangely, that's only in Los Angeles that I hear that!!! But I guess they must notice it in Dallas when I say I need to go warsh my hands before supper, and I exclaim "Duuude!!" when somebody says something extreme. And nobody in CA knows what I mean when I ask for milk. They know it as "Melk".
Charles