It's simple...really. Without long-term contracts, the marketplace will determine the success or failure of these 'businesses'. Quality will be allowed to rule. Bad 'businesses' will fail. Instead of selling the promise that 'martial arts is for everyone', and capitalizing on the constant turnover of clueless 'customers'...the shorter-term contracts actually force them to fulfill the needs of the 'customer'.
On the other hand, if you want dedicated 'students' that stick around and support a 'school'...say for 5, 10, 20, 30 years...you HAVE to offer an art that is substantial.
I see. I can't disagree with the "read the contract" thing, but well, I guess you are saying it's ok to create dishonest and harmful contracts and use it even if it hurts folks. For the record, I feel no sympathy for folks that don't read what they sign either. That doesn't make it right for folks to use dishonest business practices, which you seem to be ok with.
More and more often, it seems that we are a culture of wanting everything for nothing, that it's ok to break promises? If more people read their contracts, then dishonest business wouldn't get away with it. It's one thing if the person is injured or moves, but what about the lazy SOB who just doesn't care to motivate and go train? If the instructor agrees to teach 15 students, those students agree to pay for that service to cover the cost of the building and equipment, and then half of them don't show up, it hurts both the instructor who is stuck with the bill, and the other students who can't train because there isn't enough income to cover the costs.
Proper escape clauses should be included in any contract, injury, moving, loss of job, etc. But is it fair to the instructor to allow breach of contract just because the student is unmotivated or has lost interest? That student agreed to do something for a length of time, seems to me they should be just as responsible.