When I was a kid we used to free camp for a weekends fishing at kilcunda behind the dunes. Once a ranger dropped in to see that we had everything we needed.
We also free camped on Phillip Island a few times and was never asked to move on.
Can't do that any more.
I think the problem is these days those places are not that far from the big smoke , easy reach to the masses and so camp grounds get over used etc.
You only need to go to Venus Bay one weekend to see what over used means. That place is buggered now we never go there any more.
Funny thing is nearby where we live in Warneet there is a free camp unpublished and no warning signs where the odd MH will drop in for a few days and the locals never object.
I guess if 30 or so tried to get in there'd be problems. The place is Blind Bight foreshore opposite the local store. Awseome place.