Because it's too abstract. Laypeople can't see the constraints of coding, thus can't appreciate the accompanying accomplishments.
It takes two seconds to watch professional artists or athletes do their craft and come to the conclusion "Yep, I definitely can't do that."
Law has it even worse. Good programs may sometimes be able to wow viewers with a demo, but audiences certainly aren't going to "ooh" and "aah" over a really good contract.