Reminds me of the old joke about people (folks) who speak in letters...
M R mice!
M R not!
S A R! C DiM E D B D Is?
L I B, M R mice!
Of course you have to say it with the stereotyped hill folk drawl.
Illiteracy is not exclusive to the South or Midwest. I spent about 6 years playing mechanical engineer/maintenance engineer/machinist at one of the major motion picture film laboratories. There was a fellow there who performed building maintenance and much of the forklift driving. He was in his late 50s and could not read. He did however, possess a very broad knowledge of building maintenance and repair and was nothing short of a magician with a forklift.
Whenever I catch myself feeling a little superior to someone with a poor command of the English language, I think of some of the people I've met who while functionally illiterate, had knowledge and skills that I did not possess and were every bit as productive as I.