The grading function you are paying for is important. Otherwise you could just take a syllabus, go off and complete the work on your own and be done.
You need to pay someone to assess the work.
Whether the amount you pay for this "service" is proportional to the benefit you get from it is for you to decide.
But you need to have those "assessments" done.
Admission to a top tier institution functions as an early assessment. You gain credentials just by being admitted, assuming you manage to graduate. This is interesting since the assessment is only based on a brief period of observation, e.g. the person's achievements up to the end of high school.
A criticism that has sometimes been levelled at Stanford is that once you are admitted you can coast your way to graduation.
Obviously that is certainly not true at lower tier universities. Faculty will fail students and those institutions will not hesitate to send them packing. There is always another student to fill the empty seat.