I use geo-tracking for golf, it is accurate to within a foot. How do you think these cars self drive, it is probably accurate to less then an inch.
I was being very conservative with the argument. Even at 50 feet, the pattern is damning.
I had the opportunity to view some test data on a missile test. They used military grade GPS to track the missile. The missile was subsonic, traveling in the 400mph range. . It updated every 3 feet. Do the math on that, you see just how accurate GPS is.