Dick Smith, I am sure you can iron out this concern, or misunderstanding of mine, so please do. You said:
However I simply cannot see the point of a VFR pilot flying enroute (say, at 3,500’) having to monitor airline aircraft above FL200. On the east coast, where the airline aircraft are within radar coverage, they do not give position reports so the VFR pilot monitors useless information – i.e. no position report means that the VFR aircraft does not know where the airline aircraft is. With the NAS system, the pilot flying enroute when in the approach or departure airspace of an aerodrome monitors that frequency, and gets a good alerted see and avoid procedure
Now if that VFR pilot is flying Morrabin to Mildura at say 3,500, he follows your advice on departure from Morrabin and monitors all appropriate ATC frequencies. Then at the end of the flight tunes into the low level ATC frequencies on approaching Mildura and then switches to the MBZ. In the interim, as there is no benefit to be had in monitoring ATC frequencies "because he is flying enroute", he listens to some Slim Dusty tapes on his walkman instead. All well and good, except for the IFR aerocommander jumping out of Swan Hill for Essendon. The controller sees the potential conflict, but cannot contact the VFR aircraft because obviously as he is enroute there is no need for him to listen out.
The comment you made highlights your lack of understanding of the realities of flying. Just because one aircraft is in the enroute stage of flight happily cruising along outside any CTAF or MBZ's, doesn't mean an IFR aircraft in the area isn't on climb or descent or in the process of changing level, and thus about to upset the happy and ignorantly blissful VFR enroute flight.
Please answer this question with a straight answer and don't rollout that "Airspace at a glance" diagram for the 30th time, we have all seen it a lot of times and we are all really impressed.