Maybe not that many readers will remember, back in 1997 there was a change in procedures including readbacks. Prior to that there was only about 5 items that had a mandatory read back. The proposed changes (to bring Oz into line with ICAO) were agreed at a two day industry/AirServices/CASA meeting in CBR which had a large attendance. The problem was that the education that followed was almost non existent and we now have the problem outlined at the start of this thread.
Sadly CASA has taken little interest in radio phraseology ever since and those responsible in industry all seem to have different views on what to say and when. Readbacks are but one area that is poorly understood by many pilots from GA to RPT.(including CASA examiners!)