Xinhua
IFR twins generally have a greater speed, greater passenger load, more momentum, and poorer pilot visibility than much of the traffic we deal with around us.
Yes there are procedures and differing circuit heights etc etc but what strikes fear into the working IFR pilot - who is exposed to this 6 days/week in differing locations, traffic densities and weather conditions - is the sheer unpredictability of some light aircraft, VH or RAAus.
As someone else has pointed out, of course, there is an element amongst us who wish to fly at minimum cost, minimum effort, minimum training, and most of all, minimum risk of being found lacking (by medical examination or by imposition of strict pilot performance standards). There is a far higher proportion of these dreamers in RAAus.
There is insufficient control and discipline in the RAAus system to allow these changes in RAAus priviledges without a significant increase in risk.