Sure, but what happens when you decide you're sick of a poor salary, and you learn Python and CS in your spare time and interview for Google and then quit your airplane engine job to make 3x as much working for Google? Where is GE going to get a replacement with your expertise and experience? What happens if all the engineers at GE do this?

It seems like the only reason this doesn't happen is because of inertia: the airplane engine engineers just aren't ambitious enough to leave their field for much higher pay. That doesn't seem like a good long-term strategy for a company making a critical component of a globally-important industry however.