"Which implies (but I have not looked at the data for this particular case) that the high collision risk incidents outside controlled airspace are higher for Mode A/non-transponder aircraft than for Mode C/S.W
My understanding, and forgive me if I am wrong on this, is that there is little actual evidence of the level of risk outside CAS.
Given that many aircraft are non-radio/non-tx/non-TCAS in Class G, certainly in my neck of the woods, where do the reports come from?