I can understand some reasons for police to encrypt in their line of work, but whats a justification for a fire department to be encrypted? I can't seem to grasp the reason why a chief instructing his guys on the ground is sensitive information. I'd think a fire department is the least of any emergency service trying to keep a low profile literally making a scene wherever they go
That has also puzzled and baffled me for years. In NYC, prior to cell phone usage, when the unit on the scene wanted to transmit sensitive information, he would request "Mixer Off". This practice is still S.O.P. for the FDNY. This would turn off the audio mixer that combined the dispatch and mobile channels so that other units in the field (and civilians and buffs) could not hear the mobile message being transmitted. Of course, the very easy work around was just to monitor the mobile input frequency, but you generally had to be fairly close to the transmitting unit, depending on terrain and other conditions. Highly sensitive messages about severe injuries and others incidents go via cell phone.
My best guess is that, at least for the fire departments, they are just playing "follow the leader" and keeping instep with what the PD does. Others have mentioned commercialized incentives to sell more digital radios.
Also see my message #14 in this thread. It's not just off-duty members, buffs, family members, and others that would be impacted, but also consider the affect on the press services that constantly monitor key NYC police, fire and ems frequencies for information to disperse to the public. And many official agencies would not be able to monitor their counterparts in the other services, and that is another key reason the change has not been made.
As New York City goes, so goes the rest of the nation, so the theory holds. The FDNY's operations are emulated by Fire Departments around the world. Fortunately, thus far we have not only been able to avoid encryption, but even digital communications in the public services. I will not repeat the incident(s) many years ago when the FDNY attempted digital handie-talkie operation because it continues to stir up controversy every time I mention it, but they quickly reverted to analog. That information remains here, buried among the many wonderful threads, here on Radio Reference.