We've been over this a hundred times!
So how would have the pilot of MDX flying OCTA been able to find out the frequency of the Sydney ATC who was responsible for the controlled airspace above?
He could simply have asked for it. He didn't.
Why was it never suggested by FS that the pilot could change to the frequency of the controlled airspace above and given that frequency ?
Because it was a different airspace system back then. Generally that only happened once an emergency was declared. Radar was used to identify him, but by then it was too late. Had he not disappeared, the normal course of events would have been to get him to contact ATC and they would have dealt with him until he could resume his own navigation. It happened all the time, although you refuse to believe it. In this case, he was gone before that could happen. Reading the transcripts etc, it wouldn't have helped much anyway.
Why was all moves to use the radar properly resisted until I became chairman of CAA and introduced AMATS?
Because ATC owned the radar, and ATC ran the Department, so there was no way FS was going to get it. That was not the system you wanted, so you got rid of FS, and now ATC still run aviation and still own the radar, and you still don't have a system you want. So a win-win all round. Not.