I seem to remember that, back from the time of drafting those values up, Not For Profit is a safeguard for the learners, not the coaches. It is meant to encourage an open community where everyone — no matter their financial standing — can participate. If we were to take an entry fee for our workshops we would exclude those learners who are not capable of paying for it.
On another note, something I’ve often heard echoed inside of the OTS and other volunteer efforts is that profit destroys engagement. Our coaches love what they’re doing. If we were to pay coaches money we would quickly be in a negotiation position. How much is coaching a learner worth? Does it depend on the workshop size, or difficulty? On the number of questions answered? Which coaches do we hire? This is a can of worms we would rather not open at all.