Had a quick look at the legislation link posted by MicMack. This is a "regulation", and not the "Act"
Vic Legislation is differently constructed.
Our Road Safety Act applies anywhere, unless stated otherwise. Vic roadworthy power to inspect appears in our Act and is specific in its location. It must be used (including parked) on a road or road related area (eg footpaths etc) In Vic our Road Safety Regulations only apply to roads and road related areas, unless stated otherwise.
Reading the Qld regulation there is no mention in the section relating to defect notices does it mention being used on a road. I'm niot sure where their regulations apply. Reading it, it sounds as if it could be anywhere, or at least on the back of a trailer. (It is very difficult to read legislation unless you know how they are all interlinked. eg part A might say something, part B will clarify it further and parts C, D E may even go further into it.)
Re the Tyre Rim scenarios
You may find that it is the tyre placard that they don't comply with. The placard is the sticker that says the tyre pressures etc, also lists the rating required, and may specify LT tyres. (That is how we do it in Vic)
Would I defect a car on a trailer in Vic? No, I'm not allowed to.
Would I, if I could? Most likely not, would depend entirely on the scenario.
I am always wary of the story of a "friend of a friend" said. They sually only tell the bits they want you to hear.