I thought that the entire point of the Ohio MARCS system was interoperablilty between agencies? Ohio Highway Patrol Post 4 & Ashtabula County Sheriff's office are working on a manhunt for a breaking & entering suspect but yet each agency is using their own respective talkgroups with no patches and having dispatch relay traffic between agencies. Is it lack of training or what?
That's exactly what it is, lack of training and lack of will.
Interoperability isn't so much hardware as it is a state of mind. While having everyone on the same system certainly helps (whether it's MARCS, or conventional VHF or whatever) and makes it much easier, it can still be made to work even without a fancy megabuck radio system.
The problem is usually poor planning and/or poor execution. Even on the fancy megabuck radio system, interoperability won't work unless people know how to make it work and the will to use it is there.
In Ohio, it seems to me that the farther north and east one goes, the prevalence of the "go it alone" attitude increases dramatically, to the point that neighboring agencies often won't talk to one another at all, even if they do have the capability. It's gotten considerably better over the last few years, but examples like this are still all too prevalent.
I hate radios that require the user to look at the display to make a change. It was so much easier and more efficient to just reach down and turn the selector knob however many clicks it took to go to an alternate channel and not have to look away from the action. Unless it is easy and simple, interop will suffer.
And that's where planning and training come in. With a proper channel plan, an agency can have their most-used talkgroups in a single zone, including a couple of common interop talkgroups, and switch channels exactly as you mention.
Even so, for a long-term op, if someone has to look at the radio to change channels, so be it; at a properly managed incident, they shouldn't have to change channels more than once each operational period.