Good comment Ops,,,
You missed a couple of points though.
Flying in the Harbour at 1000' and CTR is at 1500' yet you have a piper etc 20' above you, clearly not at his level of 1500'. Encountered this many times.
People think Victor one starts at Palm beach. It doesn't. So you get some yahoo usually below 500' blasting down the beaches obvious to any other traffic.
SHS are not the only traffic at Cottage point etc, so the radio calls are for every one.
When you are in a valley a couple of hundred feet wide below 500' and there are other aircraft about, wouldn't it be nice to hear them. At 3000' feet what are the chances of being in the same airspace at the same time.
The number of times I could see the face of a pilot in another aircaft, knowing that he is not on the correct frequency is beyond a joke. I have followed a piper at 400' from Gosford to Sydney harbour only to hear him on the correct frequency passing Bondi beach, god only knows what he was doing for the previous twenty minutes.
As for SHS pilots using a company frequency I believe they do, the only reason they talk on the other frequecies is avoid coming around a corner face to face with some other low level wanna be
"betta to be a dill than a doh any time!!!"