I work at a gym and we ask for almost the same amount of info. The reason they ask for all of it and a social is so the gym can collect the money owed if you default on payment. I'm sure a lot of the larger franchises sell personal info though. We will allow people to pay in full or go month to month without providing a SSN. The planet fitness near us only takes bank account info and will not take c/c's. Credit card #'s change all the time, most people bank account #'s don't so it's easier for them to collect the monthly dues.
