Not entirely worthless. To clarify, the LAANC zero grid area, typically located around airports (although in your specific instance, it's a military restricted area), restricts UAS from entering that space; however, you have the possibility of...
This is because GPS altitude is based on an ellipsoidal approximation of the earth's surface. As you have found it can differ 100s of meters from actual altitude and is not useful for the altitudes typically flown with drones.
I doubt there's another country in the civilised world where the term mainstream media is used as a pejorative.
Whenever you see that term being used disparagingly, you can tell a lot about the person using it.