I blame religion. Religion is big down there. It's a big business. Religion depends on numbers for it's income. Each church, Parrish, cult, or congregation, is in competition with all the others, for members and their dollars. Keeping a congregation ignorant is a good way to keep them from exploring the world around them. Most preachers tell their congregation, that education isn't important, and that everything they need to know is in the bible. And the preacher will read that to them on Sunday.
I never went to the grocer store, without seeing someone give the clerk their check book to write in the amount for them. It wasn't unusual to hear mothers berating their kids for trying to learn to read. At the DMV, the line where they read the questions to you stretched clear out the door, while all the other stations were empty.
Survived 7 years in Ft Mill SC