They can't. And, there are others.
They can't tell the difference between an economic system and a political system. For instance, they don't understand that "communism" is an economic system, and "dictatorship" is political.
They can't tell the difference between teaching something, passing on the knowledge, and promoting. For instance, if Islam is taught that's promoting, and the same with communism.
I think it's a structural problem, the result of relying upon strontium 90 instead of iodine in ones diet from youth. Everybody knows conservatives love strontium 90.
Arf