These forms give the spa necessary information, but they're also a protection for them. If a client brings a suit for some reason, the spa has the form specifying the client did or did not disclose certain information and requests. I would never run a spa without having a very detailed intake form. That's just asking for trouble.
I also think it's a great idea for the spa to have a list of guidelines the client must read in order to have the services done. It's also a good idea for spas to have therapists work only with clients of the same sex, to avoid charges of sexual misconduct on both sides. That's just common sense.