I voted you back up. But the answer to your question is 'for the same reason you don't teach GR as a prerequisite to tying shoelaces.' Small children and shoelaces wouldn't be here without GR either, but it's just too abstract for most people.
The problem for the poster above is that if you read SICP outside MIT or especially outside college, you're not surrounded by a bunch of science nerds who can be persuaded to explain general relativity in return for beer and a pizza. If you're not swimming in a sea of science, then problems involving the behavior of fish seem much trickier to solve. I've seen this problem iwth a few other MIT books, eg Horowitz and Hill.
Horowitz and Hill? Hmmm, I don't remember running into any out-of-domain stuff whilst working with that book at uni, but then maybe that's your point - I was at uni, so it fitted nicely, but for someone coming at TAOE without an engineering background might struggle. Do you remember any concrete examples? Was it something like needing to understand wave propagation to understood why the modulation circuit worked, or things like that?
I'd have to go and dig out my copy now to check. The main things I remember offhand were problems with no discussion of the answers, and examples of 'bad circuits' which you were encouraged to build to find out why they went wrong. Great if you're in a class, not so great if you're studying alone.
