I know that if my students go up to summer camp and they do not perform at the level they should, I'm the one that pays the Shihan on the mats. I'm the one that gets to take Ukemi until I can't stand and take all the really hard ones. That's why I won't pass anyone who doesn't perform way above the level that is just acceptable.
But then, I also pay if I am being too hard in the gradings when subbing for my Shihan at some testing. I have a keep a good balance and know what he wants, I guess.
So in some ways, the students pay for me to take their punishment if they screw up.
I remember the trepidation with which I would always get up when Tohei Akira Sensei would ask during some student's testing: "Who your instructor?"
Now, I would have to stand if Kawahara Yukio Sensei asked: "Who tested you for your last rank?" I think that public humiliation would be worse than any pounding I take from him.
But money is a poor substitute for honour and reputation.