Fine for using a postage stamp…

We are all familiar with the system where the Post Office charges us extra for an ordered item that is not franked or has insufficient postage. This used to be done with postage due stamps. But the United States Postal Service, the USPS, came up with a surprise on January 12, 1983! A series of 7 stamps, a postcard, and a pre-franked envelope. Nothing special? The series of stamps and the two postal stationery items were intended for use by government agencies in the USA. They served as a test for a new settlement system between the USPS and official agencies. No service stamps had been issued since 1911, so this was completely new to American collectors. The stamps, in denominations of 1c, 4c, 13c, 17c, 20c, 1 dollar, and 5 dollars, were designed by Bradbury Thompson of Riverside, Connecticut (he was a member of the Citizen's Stamp Advisory Committee) and were only available in Washington, D.C. But collectors, of course, also had a need for these stamps and stationery. Therefore, they were also available through post offices with a philatelic counter. To prevent the stamps from being used by collectors, a warning was placed on the stamps and stationery: fine of 300 dollars for private use! That warning was also printed on the 13c postcard and the 20c envelope. The imprint of the stamp value on the envelope was applied in a special way: in relief printing. And the 20c stamps were issued in rolls, so they were unperforated at the top and bottom. Were the stamps and stationery used by private individuals despite the warning? I have never received a letter franked with such a stamp. Perhaps you have? And who paid the $300 fine?