Rhys: We have Class E under Class A as well. Not just C.
Happy: Advising or not advising of VFR traffic are due to any number of factors. If you listen to the controllers for Ballina (120.3) they will always let the big guys know of any VFR's that look like that may get in the way of them. However remember you have to be identified for us to do that. If you are under 1,500 ft there we wouldn't necessarily see you. That's just one example of an aerodrome. Each area is completely different due traffic, airspace, controller workload etc. Ie. If an IFR flew into Caboolture I don't expect the ATC to tell him of each VFR in the area, he would probably be there all day...