I'm not sure I can fully agree with the idea that programmers are self-taught in the sense of writing good code. I'm a student at the University of Waterloo, and in the courses in 1st and 2nd year a sizeable chunk of the marks depends on readability/documentation and such. We have coding guidelines and we lose marks for not following them. Needless to say, this doesn't mean most students at Waterloo write good, well-documented, readable code. Most of them are focused on getting the program to work, sprinkling in obvious comments (i.e. "//setting width to 60" ) and debugging when the tests fail. When they get marks off for poor documentation/readability they either complain or brush it off, claiming that since their program worked the rest isn't a big deal.

Bottom line: in my experience, the reason most programmers are self-taught with regard to writing good code is not that no one tries to teach them. It's that most of them don't think they NEED to know (i.e. don't place enough importance on it) and are willing to lose marks for it until they get to a job and they have no to choice but to, you guessed it, teach themselves. There are people who try to make the best out of their education, and these can be very good coders who learned by making the best of their education.

(Note: obviously this is a generalization - there are plenty of students who try to write good code.)