Is this just your belief presented as fact, or do you have some data to back this up?

(Not the literacy stat but the fact that illiterate people "figure out how to use tech by memorizing the icons and locations of buttons").

Well, if you're unable to read, you're not going to figure out what the buttons do by reading the textual labels :p

Further, if you have difficulty reading, it's easier to parse the meaning of an abstract symbol, so you'd use that instead of a textual label when available. (I say this as someone who is a really slow reader. I use icons when I can)

Watch a small child use a computer.