In fact it is just time shift technology, simple really if you can handle the physics involved.
One could chase ones tail all over the place seeking to validate a rational response to the technology available to the designers and owners of the GPS system but it is factual that they ( THE U.S. Government ) "own" the system and despite all the heart felt angst, they will do with it ( the system) as they ( the government) see fit and the rest of us can cry unfair till our lungs dry up, face it the system is theirs !!!!!!!!!