SECOEMS,
We're in Oklahoma, where the terrain looks more like a pancake than a mountain. There's a 2m repeater on a 200' tower near me that I can work for over 100 miles in all directions with a mobile.
The Sapulpa dispatch console can hit Bristow and Preston because that's tower to tower, and while they aren't 200', neither are any of the hills, and they're all in a 50 mile circle. But a mobile with an antenna 5' up won't have near the range, and can actually be "between" towers/sites if the conditions are just right (or rather, just "wrong", from the users point of view).