Some (many) users actively refuse to learn. There appears to be some psychological barrier that prevents them from even trying (perhaps similar to how some people panic at seeing any math beyond simple addition arithmetic). That's not to say the people are stupid - many of them are relative experts in some other domain, but yet when a computer interface is presented, they shut off their brains.

While I find "wizard" interfaces frustratingly slow to use, I think they are a better approach for many users. Here's a silly but not so terrible idea for an email interface, wizard-style:

1. "You have a new email from bob@example.com. Would you like to open it? [Open] [Save for Later]"

2. (opened) (display email). "Do you want to reply to Bob now? [Reply] [Do Something Else]"

etc. etc.

This kind of interface could be handled by anyone, and it would probably work well for people with different physical or visual challenges.

Anything more complicated than this is just beyond the willingness or capability of most people to handle. What's really scary is that some people operate their cars much like they operate a computer - doing unnecessary ritualistic things that have no benefit or produce the desired outcome as a side-effect, leaving some systems in a permanent state when they should be enabled/disabled at different times, and so on. The tendency is to think that people are just generally incredibly stupid (unwilling to learn, not incapable); but perhaps it's just that our UI approach needs to actually be two approaches - one for users, and one for refusers.