Why do they teach calculus?
Why don't they teach Fast Fourier Transforms instead?

Far more useful. High degree of applications.
And really matches what we see in the universe.
Wave patterns everywhere.

Calculus, in comparison: Everything useful has already been computed. Just look up the formula.
Knowing it doesn't help you at all. Its like showing your work when you've done it a hundred times.

Well, i discussed why the teach calculus first in my first post on STEEM
and it is to destroy your brain and get you to never question math(amagics).