The driving schools are a huge lobby group in the laws regarding getting your drivers license. After I got my license, they successfully lobbied for a mandatory lesson for instructors (not too expensive, but still not a small income). Learning stick shift is harder, and takes a lot more practice. There is probably some economic interest in having people learn to drive stick.

The only AT cars that I know have better fuel economy than good manual drivers are cars with CVT (continuously variable transmission). They are expensive and not something I would fix myself though :)