The big deal is this - not everybody is using modern, narrowband capable, radios.
I am on the Statewide Firescope Communications Specialist Group, and this topic comes up just about every meeting.
Small Volunteer Departments most often have outdated, non-NB radios, and almost always lack the funds to upgrade. Then, when they get called for a Mutual Aid request somewhere where there is narrowbanding (i.e. any Federal Forest area), there is a conflict.
Another area of concern - I am a certified Incident Communications Manager, and spend time evey summer out at the Campaign fires around the state. Almost without fail, we get private contractors (Dozers, Water Tendeers, etc.) that come to the fire with old Bendix King LPH and early EPH radios, that can not be programed for NB or split frequencies (which are not neccessarily the same thing). These radios get rejected outright, or at least they should, and if we have them, a radio is checked out to them from the cache. Of course, often we have no radios to provide them, so either they get demob'd and sent home, or get sent out to the line without a radio (*very bad*). Worse are the contractors who know their radios are not capable or authorized to use, but hand program them off the ICS-205 that is in the IAP, and go out anyway. This can, and has, cause all kinds of issues - especially under emergency situations.
I am not sure what the solution is - nobody is. It comes down to Safety vs Cost vs Personal/Department desire. If somebody figures it all out, let the rest of us know . . .
Stepping down from the soapbox now.