I've done support for sysadmins and I've run into a lot of them who don't understand the concept of relative or absolute paths. A couple weeks ago I had to explain how password hashing works to people working for a huge aerospace company.

I think most people learn to use computers like they learn to use a car, in that they understand the rituals they need to perform to get it to do the thing they want. They lack understanding of what's going on under the hood so when something goes wrong they can't fall back on knowledge and figure out what went wrong, they have to learn an entirely new routine to fix it instead of learning the principles and thinking critically.