For what it's worth - Television comms can be amazingly complicated. Huge teams of people with totally different needs. On big events there may even be a small team of people who's job is to route the right talkback to the right destinations. Cameras (that is usually my area) listen to one person in the main - the director, but most of our speaking need is to talk to 'racks', the people who in laymans terms, expose our pictures. These engineers match the sources from the cameras - and they can interrupt the directors talkback to us, and we reply. We can also talk to the director if a direct question is asked, but we don't speak much. The commentators get the director in one ear and the programme sound in the other. The VT people (who of course haven't seen a tape for years now) need something else, and so on. The people without cables get continuous talkback, but their PTT button might go to the gallery/OB control room if they are perhaps a floor manager, but somebody else might send to the engineering guys, the sound people or lighting people - depends on what they do. The gizmos I use have ten line level inputs, and ten line level outputs - and the lights flash when people are speaking - so you hear a voice, look at the panel and see who it is - then you hit a button to send your voice to any of the 10 destinations. On top of all this, somebody decides if your voice from say a camera, or a floor manager needs to go out to everyone again, or be one-way. Like a repeater. It only takes one wrong setting to wreck the entire thing.
When you listen to the radio outputs, what you hear may well be the director - but the chaos is actually quite ordered. In rehearsal, people will often reply, and ask questions - who is then talking to whom is confusing. Once it goes to record or TX mode, generally, everyone bar the director and the production assistant calling the shots shuts up. Talking back tends to be only for absolute essential stuff like - "The guest isn't here!"
If you listen in to your local theatre, most pro venues use cable for their comms for the shows. A few have a link to walkie talkies, but not many. The stage crew use their radios for point to point stuff, and the show running is separate.
If you want to hear the interesting things, then you should be listening in to the radio microphones - very low power, 50mW or so, and dotted around the old TV channels - these can be the mics, but also the in-ear monitors you see people use when they are performing. If you are close to a venue or other performance space, these are in common use. Look in TV channel 38/39, 70 (for the license exempt ones) and in other TV channels that are unused in your area. You'll need a WFM receive setting, and some will be stereo, but these will still be listenable, in mono as they use a similar stereo system to broadcast FM. You will probably find multiple channels in use - 12 to 14 is fairly common. The transmitters are permanently on - the actors do not touch them, so they are always live. I'm surprised the nasty daily papers don't seem to have noticed this. Most shows now have a person dedicated to listening to these to maintain quality, notice battery issues and fix them before they get bad. They're all linked up and networked - but a scanner outside the building will hear all this - totally in the clear. It's also quite possible for the system to be used for crafty purposes. One show I do fairly often has a crooner, well over by the lady fans who talks to them as best friends in between songs. People have sent in cards saying it's auntie flo's 60th birthday and she first saw the star in 1961 in Liverpool. The sound guy at the back simply says into a mic, AUNTIE FLO IS HERE - the fella on stage hears this in his ears, and mentions it. The sound guy says SAW YOU IN 61 IN LIVERPOOL, and the fella on stage says - where are you? She waves, then he says - I remember you, you were at that liverpool show we did, when was that? 61 or 62. She feels majorly special, the audience think he's amazing and so kind.
As for mediums ..................... One did get caught a few years back using exactly this system.