Apologies on not using accurate terminology wrt being stepped up solutions but;
the technology is available to stop dual transmissions, even a warning light in the cockpit (ATC station).when simultaneous transmissions are being made would help safety.
On the collision avoidance technology the CAA gave a grant of £250 towards the cost of approved FLARM devices one of which I have - XC TRACER MAXX - which also has FANET.
The swiss invented FLARM nearly 30 years ago and marketed it at cost; it has been obligatory in France for glider operations for the last decade. According to the CAA website it is better than the ADS-B out.
The telecommunication industry has come a long way from the necessity of climbing into the electrical bay and re racking or thumping a radio module but basic cockpit radio procedures haven’t.
What appears to be also relevant is the language and associated phraseology; there was a narrow airmiss in Dublin between an executive jet on take off and a private helicopter pilot caused by ambiguous crossing clearance issued - cross behind the rolling aircraft IIRC which the helicopter pilot took to mean the aircraft rolling down the runway after landing whereas the controller meant the executive jet about to roll; the copilot stuffed the stick forward after take off and passed underneath helicopter.
In this accident I presume that all were Americans; flying around a southern French airfield the controller standard can be diabolical.