Medical != medicine. Physical therapists provide therapeutic interventions. Doctors of Medicine (M.D.) practice medicine. This is why they can prescribe medicine. Same with Doctors of Medicine in Dentistry (D.M.D., also known as Dentists).
Psychiatrists are also Doctors of Medicine and can prescribe medicine. Other mental health professionals (Licensed Professional Therapist, Licensed Marriage and Family Therapist, Psychologist) are not and provide therapeutic interventions.
EDIT: I just realized I'm coming at this from a USA-centric point of view. I have no idea how this applies to other places.
I'm sorry, but going to a quack doctor is not medical care, much like McDonald burgers would not be a healthy meal regardless of whether or not that's all you can afford.
Except at least in the McDonald's case you have to eat food to survive, so you may not have a choice. You don't have to go to a chiropractor to survive, so it's better to not go there at all than it is to go and receive possibly dangerous treatment from a con artist.
Remember, there is no science behind what they do. They don't know if they're going to hurt or paralyze you because they never went to medical school!!
Oh, well as long as they're only practicing medicine without a license, I suppose that's okay then...