Try joining a health club... you pay whether you take advantage of it or not. No one thinks this is unusual because that is the way clubs work. You pay or you quit.
I assume in a health club they're required by law to include the terms of payment and of membership on the form you initially sign to get a membership.
In some of the cases being discussed it sounds like the person wasn't even told _verbally_ that there was a rule until _after_ they had not payed (e.g. someone taking several months leave of absence). That's no good.
People talk about a contract as if it's something slimy or 'corporate' or 'lawyerish' or something. It's not -- it's good communication. It's being honest and straightforward and making sure that everyone is on the same page from the beginning. You don't have to call it a 'contract' if you don't like the word, you don't have to write up all formally and legalese, but for goodness sake include any info that important on your registration or info forms and make sure everyone understand how things work at the _beginning_.