For others and the OP
This has been a hot topic for many years and well discussed over the years since the Internet opened to the general public. The following is my understanding of the campaign and the results
There was a point in the early 70's when Ford (concerned about a possibility or as a result of lawyers or other things) sent out millions of these decals. With a letter of instruction there were sent to every registered Ford owner. At the same time dealers were provided with allot of decals and instructed to place one on every car in the dealership (new and used) as well as any Ford product that came in for service - with no end date to the program so no idea of how many years dealers continued to do it but the decals were provided for years.
As another facet of the program a decal was included with every service replacement radiator shroud.
As a result we often see very low mileage original cars with them and in sheer numbers just allot of cars with them. Because of this, in the early 80's they were accepted by most people as original and often original owners swore "its always been there". We've learned allot since those days and today the decal is often used to describe a lower level of restoration in some circles.
Sorry for the long answer