I agree with you whole-heartedly about the frustrations of IT work. Hence I decided to leave the field. But my stance at some point became viewing computer illiterate as just that, illiterate.
Do I mock those who can't read and write? No, I help them and volunteered at a library once upon a time. It is a vital life skill that they somehow missed. Just like computers are these days. So while I completely agree with the frustrations, I got a lot personally out of stepping back and looking at the situation objectively.
Past equating it to adult illiteracy, you could similarly compare it to a child not knowing how to do X,Y, or Z. Some people/children were just not taught something or another. It happens, 'teach a man to fish...' type thinking might be helpful. Blame the parents, society, and the person for failing to realize at some poit that 'oh snap, maybe I should figure out this whole computer thingy.'
But god, oh god, sometimes you just wanna take that mouse cord and wrap it around their 'I didn't know I shouldn't open e-mail attachment' necks. Though with bluetooth and other wireless mice being the rage now a days, what might I use?
/ciao