Not commenting on this general thread.......
Not commenting on the sometimes GPS accuracy in the US.
Example......decades ago........seeing a track that went from Harris Hill to Europe and back.....in a few seconds. This while the glider and tracker were sitting on the grid at HHSC.......
I was there.
I saw the trace.
Pretty much NO WAY any government could cover that ground in that time.
I believe it was called, "military dithering" of the signal, because, government.