Not necessarily, however the alternative is to have it 'engineered' by a certified engineer who certifies that it complies with all relevant ADRs (Australian Design Rules). If you think that this can be difficult and expensive, you'd be right.
Far, FAR cheaper to just pay the toll and buy from a supplier who has had their design and build certified. One must not remove the compliance label/plate either!
Same thing applies to all trailers and caravans made since 1988.
Both my roo bar and sump guard were made by SubaXtreme, and have the relevant compliance certificates/plates. These compliance plates state both the make and model of vehicle, and the device is not certified if fitted to any other make/model of vehicle.