And as far as average traffic densities being light in Oz...very true until you get real near YSBK,YBAF etc. And yes even BK on a busy day probably doesn't compare to any number of US airfields...but we still had a midair at BK last year.
The link below makes interesting reading and, except for the place names you'd swear it was Australia...you'd think we already have the North American System!!
Michael Maya Charles on the Denver midair collision
Chuck