The only problem is: not all doctors are subscribe this universal database. The coupon is good for people have no complicated prescriptions like you have mentioned.
No, the problem is that there is no universal database.
The coupon in not the problem. The problem is the fragmentation of the information. In some cases, if you are not careful, the coupon can increase this fragmentation. If you keep all of the information together, by transferring all of your prescriptions in this case, then there is no problem. If you fill your prescriptions at different pharmacies based on the prices of different meds then you may be creating an unsafe situation for yourself.