They can't, this is the only common freq between the military units, the police, and the hospitals.
You may note the large number of people instructing others to call them on cell phones, though. I'll leave it to your imagination as to why.
if it's a seperate freq, ok, but dangit, I just hate for that stuff to go out over the radio ... in the military that'd be considered classified info, even going over modern crypto equipment..