Why should the airlines, military and top end IFR have to fund providing a radar infrastructure that they don't need to just because the minority don't want to pay out on new kit for their aircraft?
Pontius, the people you quote have the means to fund the infrastructure and except for the military, are commercial operations that recover the cost in their fare structure.
The system as we know it has worked well with procedural separation outside of controlled airspace. Further, we have such a vast expanse with bugger-all GA traffic operating IFR, the chances of a mid-air are exceedingly remote.
In my case I've spent 22K to install TCAD and I'm reasonably confident I can detect and avoid any aircraft, always providing they have a working transponder (that's also been switched on). Thanks to CASA and their over-the-top approach and early introduction, I'm held to ransom by Garmin and Mooney if I choose to bring my G1000 panel up to ADSB compliance. A spare $45K would do the trick.