Many illiterates are not stupid, just unfortunate. Many illiterates function at a level of inventiveness and adaptibility that we cannot begin to imagine. I know a lot of alliterates, people who can read but don't, who spend a lot of time engaged in useless activities attached to what little they are willing to read that would be proven unnecessary if they engaged in a little research. But research involves thought and many alliterates have never learned to associate reading or writing with thought. I know it is a strange concept, but just think of 'monkey see, monkey do'.

I encountered a customer at my work last week who was looking for a phone reload card. She grabbed the right one, based on her ability to recognise the colors and the emblems, but she asked for confirmation. She informed me right up front that she couldn't read.
Later, she asked for assistance in selecting a box of condoms, saying that not only couldn't she read the boxes, but she had never bought any before, having spent most of the last two decades married to someone who provided them whenever necessary and she hadn't had to give it any thought. I have had illiterate customers before that I was aware of, including two men who were brain-damaged in auto accidents. I don't know how many of the rest of my customers are illiterate because it has never come up and they are probably so adept at their adaptibility that it is not obvious.

Functioning as an illiterate requires pattern recognition and a good memory. One would think that these skills would also allow one to eventually learn to read, but one would be wrong.
I know people who have been driving an auto all their lives, including dribbling go juice and an occasional bottle of lubricant into it, who don't know anything about cars. Nothing. Some can't even tell you the country of origin of their vehicle. Other's can't tell you what sort of engine is under the hood. I personally cannot imagine owning a vehicle without having done some research into it's company and design history before or behind purchasing same. I cannot imagine owning a vehicle without knowing that it is front or real wheel drive or even if it is a standard or an automatic.

When I was a child I knew several illiterates. One was a certified idiot and another was an old man who apparently had been working since he crawled from the womb and never had the chance to become formally educated. I hear there were a few kings and queens in history who were very similar in their reasons for being unacquainted with the written languages of their subjects. Yet, both of these fellows that I was aware of were functioning members of society. One sold newspapers door to door, an ironic turn of events if there ever was one, and the other married a woman with a college degree.

Oddly, I can understand illiteracy and the way it influences one's life. I am numerically blind. I have enormous difficulties with math on the most basic level. Multiplication, division, addition and subtraction are arcane mysteries to me and yet I work with money. Simple monetary transactions elude me, too, and yet I work in retail.
It is through repetition and memory that I have been able to function on a very basic level as a clerk in an inconvenience store. I recognize symbols and I recognise patterns. I also have suffered some experiences often enough to be actually be able to memorize some things and let my muscle memory deal with others.

I am pretty close to being functionally illiterate with regard to computers, also. I can mouth the words and repeat the phrases, but computer programming is a mystery to me. I know basically what it takes to make these curious little characters I am making appear in this white space become almost reality in cyberspace, but I cannot sit down with a piece of paper and begin to make a list of what I would have to do to go from that piece of paper to a functioning device that would allow me to sit in Temple, Texas and tap on a plastic keyboard in order to make letters appear in a blank square on a server in the UK. It took me almost six months when I first got this computer six years ago (yes, I still have my first internet-ready computer) to learn to 'cut and paste'.