GPS offers those with the proper user equipment a NAV solution, plain and simple. How that is used is up to the, well, user. And yes it is global, so the problem with "out in the middle of nowhere" is LOS, just like in a city. Very few "enterprise grade" applications require true real-time data, which is why most don't get it. It is not worth the extra expense to go farther than near real-time. But those that want it can and do have it. Plus, I would expect this application would have access to whatever equipment they needed - some that is not generally available to the public.
BTW, I should mention that I worked in the GPS Joint Program Office for 9 years (4 Active Duty, 5 Reserve).