There are therapists where I work and it is written in the guidelines the patient signs at the outset that if they cancel with less than 24 hrs notice, they either have to pay a cancelation fee OR they can bring a doctor's note and be excused from paying the fee. I have never heard of anyone bringing a doctor's note, though. I guess it is left up to each therapist's discretion. The policy is made by the administration, not the therapists.