Flying bing hi. Gps is very easy to jam. Try using one near a US warship with its "gear" turned on.
Frank, the trouble with your " big skies " theory is that most people fly point to point, and if they are navigating via GPS and using aerodrome reference points as waypoints then you can guarantee they will track identically and you had better pray for sufficient quadrantal altitude discipline.
I've had that happen to me, which is why I now " fly all over the sky" and always offset from recognized waypoints.
I guess we will get WAAS when car drivers and miners need it.