Crab,
I think you are trying to push water up hill without a pump and your comments together with some you and your colleagues have made on other threads shows holes in your knowledge in civillian ways. There is nothing wrong in that - I never knew military radios constantly monitored guard.
One of the problems with 121.5 is that ppls used to be (and may be still are) taught that reception is poor below 2000' everywhere and very patchy north and west of Manchester. Now I have no idea how true this is, but it is a perception held by many.
To up grade every civillian radio to ones that monitor guard is a non starter without regulation and to be effective would have to include balloons, gliders, microlights, hanggliders and those parachutes with fans on. Not very practical. Remember that there are huge number of aviators who do not fly with a radio at all.
Unfortunately the current TDA system is flawed, I flew unwittingly through the TDA set up for the Hatfield rail disaster, but there is no way I could have known since it was within an hour of it being first NOTAMed (and I was completely unaware of the incident, so you can't accuse me of rubbernecking). Fast jets fly through TDAs set up for SAROPs - I have seen it happen. I am sure you or at least some of your colleagues have seen it too. We can all only do our best to avoid these areas, but when they are set up at short notice and there is no guarenteed means of communicating the information to airborne craft, then TDAs will get busted.