What's wrong with gym contracts?
No, many little independent gyms have caught on to the behavior too.
When he cancelled he was informed he’d actually been on a reduced rate based on an expected 10 year subscription, and as he hadn’t stayed 10 years, the price had actually been $60/month, so he now to pay a one-time fee of $10/month for every month he’d been with them, in order to be able to cancel.
Or, if he couldn’t afford that or didn’t want to pay, of course he could withdraw his cancellation and keep on paying his $50/month fee.
There are a few gyms that don't, but these tend to be based on personal training or snall group classes. That personal attention means they are more likely to end your contract for you if you are not attending as they need a good reputation to justify the high price they have to charge everyone.
If you know what your are doing in the gym you don't need the services of the more expensive ones, so canceling will be hard.
They rely on the fact many members will go less and less each month before reviewing and cancelling, so they get paid for 5-6 months.