They want to be recognized. They want ease of transaction. A business spends mega dollars to distribute a coupon. The employees should be aware of it and know how to process it. Provides advertising for local Burger King.
Concept actually attracts business for the doctor - via patients telling friends of plan.
Encourages doctor and staff to do more effective scheduling. Easily executed and evaluated. Pre-emptive procedure to overcome competition. Easily conveyed as a promotion message. If you fill it out and turn it in when you pay your check you receive 50 cents refund on your bill.