What you have to look at is the “mix” of VFR aircraft with regional airlines. It is obvious that over 95% would have a proper engine-driven electrical system. If you capture 95% of the traffic with a transponder, that is a hell of a lot better than zero.
I don't understand the point you're trying to make. As far as I am aware, no-one is arguing for zero transponders in class E.
What I'm saying is that if you are pushing the point that class E has a high degree of safety
because of the 'mandatory" transponder fitment then that is incorrect, because my interpretation of the regs is that many sports aviation types can now operate in class E in VMC
without a transponder [if they have no electrical system capable of powering one] and no communication with ATC.
From the exemptions list, in addition to gliders these sports aviation types include hang-gliders, some types of ultralights, trikes and gyrocopters. I have no idea, but the number of these in the country might equal the number of light aircraft.
So your assertion that 95% of the aircraft operating in class E will have a transponder is debatable, particularly over time [and in the vicinity of places like Albury], and where class E corridors are extended down to the circuit area of aerodromes.
I suggest that regional aircraft mixing with such types, largely invisible and nil communications isn't an acceptable situation.