> On the other hand they get paid based on how much value they add.

Nope. That only happens if they're scarce. If they aren't scarce (or are otherwise deleveraged) they get paid minimum wage regardless of the value they create.

> Someone whose skill is French Language is surely is not much worth compared to someone who knows how to make pancakes.

You seem to be awfully certain of that. Unless you meant to assume what you set out to prove (French lecturer is poorly paid => there isn't demand => poor pay is justified) I don't understand your argument. Clearly there is demand: sum up the price paid for the French credit by all the students in the class. There's just a middle man that skims a tremendous amount from the tuition paid for those credit hours before the money reaches the teacher / support staff.