two things; - I think it boils down to people not having 'poked around'. I grew up on DOS / early windows, when messing about, learning commands, configuration files was needed to install and run games (or new hardware). New game, new challenge. This learning process was part of the use of a computer to me. It gave me enough confidence and knowledge to 'try things' in later Windows or software if things were not working. To most people i'm a 'computer guy', yet when it comes to Linux / unix / mac I have no idea how to get around.
- being overwhelmed / debilitating alienness (for lack of a better word), when they dont have adjacent knowledge & confidence. It's not just the transfer of knowledge, but often a çomfort of familiarity that is needed. My wife was a basic computer 'user' who would panic or blank out when she got simple technical instructions or something went wrong. I quickly learned that it was more helpful to show her we can just poke around, and it's ok to not completely understand something. We talked about how to communicate computer problems, and effectively use google. She got over the 'deer in headlights' syndrome, and now actually welcomes any new computer topic - while working in IT service desk!