Shouldn't the course be designed in a way where everything on the exam has been taught in the class? People with prior knowledge will still have an upper-hand

Shouldn't the course be designed in a way where everything on the exam has been taught in the class? People with prior knowledge will still have an upper-hand in everything (even beyond school), so I'm not sure that it's even a solvable problem. I guess perhaps one could give a baseline exam on day 1 to qualify prior knowledge and give a handicap to people if they're coming in blind? Though if I knew that purpose I'd game the system, so it probably still isn't fair.