Let me give an example that can illustrate this: a typical mobile plan from Verizon in US costs $45/month and gives you 15 Gb of traffic. At the same time in Russia one can get 30 Gb for $9/month. Are expenses for maintaining a cell network 5 times higher in US? Unlikely. It is just customers in US are richer and are ok to pay more for the same service.
I don't know how this effect is called, but couldn't the same thing happen to education, land or housing costs? These are obviously things that everyone needs desperately so the seller will squeeze the maximum they can, and the price is unrelated to how much the lecturer earns or how much the bricks cost. The house will cost you almost all your life's earnings no matter where you live.