In the USA their MOAs and restricted areas are generally in the “triangles” that are created between air routes, and most are out over Arizona or Nevada where the traffic density is lower and therefore the number of diversions is less.
The MOA I used to fly in regularly was smack in the middle of North Carolina; one of the highest traffic density areas in the US. We regularly had bug smashers flying through the middle of Air Combat training. It was more risky (for all concerned) and definitely lowered the training benefit for the Air Force aircraft.
MOA's ARE MORE DANGEROUS THAN RESTRICTED AIRSPACE - FACT
We also had commuter airlines and lighties flying around our USAF base traffic zone (I think the zone was only 5 miles but I cant remember exactly) and were often given traffic on them (we were on UHF, they were on a different VHF) but in the haze we would often pass through 'ships in the night' with no visual and no radar paint. The risk was increased when you were dragging a 4 ship formation through the area. So the airspace can be less restrictive, but it is impossibe to deny that the RISK DOES NOT INCREASE
Mostly they are not following pre-organised routes (as per the USA) and the safety is obtained from the fact that the probability of hitting one in most parts of Australia is extremely small.
Wrong. In the USA you cannot plan and fly a low level route of your choice, you can only fly on a pre-planned VR route. They are usually 5(?) miles across or so and are extremely restrictive as far as training benefit is concerned. The RAAF currently has access to an extremely less restrictive and more beneficial system.
If the rules were updated to those of other modern aviation countries, there would rarely be any holding in the lane.
So what you are saying is that if the rules were 'updated' there is still a chance that there would be holding - so how do you determine that in this case the holding will be less than present; what is the benefit vs impact to GA / Military operations???
The rules could be changed to allow Dick to do what he wants; but it will increase the risk and it will impact on military operations (they would probably carry more fuel reserves as an example), so whilst anything is possible as always it would be a balance.
You mentioned traffic density yourself Dick; in the US they HAVE to share in a lot of circumstances; we can still afford to be more restrictive and therefore be SAFER and continue to provide the most effective training opportunities for RAAF crews; at the cost of very SMALL inconvenience to GA.
One possible reason for a reluctance to provide a coastal lane (i.e no clearance required) would be when the RAAF wishes to close the lane; you would be running the risk that you would have aircraft transiting the (de-activated) lane without any idea it has been closed - this again would be an increase in Risk. I am not saying this is enough reason not to have a lane; but it is a factor in the risk/reward decision.