You are right and I agree with you 100%, but it's not just them. Most gyms do this; all require contracts. My thing is why not just charge me each time I visit or even better, month to month when I come in (like buying a "gym pass" for 30 days or whatever).
The best solution is to buy your own gym equipment. Get one of those multi-workout systems (I won't mention a company or specific model cause I'm not trying to promote anyone in particular). But I can tell you, being able to work out in the privacy of your own home on your own time is FAR better. Plus, most of those companies that sell the workout machines will send you workout videos or booklets that will teach you how to use the machines and what exercises to do to work specific areas of your body. Anything else you want to know you can find online. And like anything else, once it's paid for, it's yours forever so no "renewal" or "membership" fees.
Shop around and find what fits best for your workout needs and for the best price. Set it up in the garage or an extra room if you have the space. Trust me - I quit the gym years ago after similar hassles and have never looked back.
Good luck to you.