If you need a Computer Science degree to operate a CNC lathe, no lathe would ever be sold. If I were to write the system to control a lathe I would make it "money-see-monkey-do", like generating a keystroke macro. The operator would make a cut and the machine would learn and make a 1000 more exactly like the first one.
It's mostly a job for the operators or product designers to make the scripts for those machines. I wouldn't be surprised if software like AutoCAD can generate the scripts for the more common brands for you based on the design files for parts.
As Vadriaan says, they're mostly simple languages/tools that do little more than allowing the user to put in sequences of movement and tool use. Something akin to
move left 10.0
move up 1.01
select head 100
move up 2.05