Australia being so big is one reason they have such fees. There is a huge imbalance between the state capital cities and the rest. Eg Perth metropolitan area (not including Mandurah which has 78,000 but is part of the Perth metro rail system) has 1.55m people which is 75% of Western Australia's population. Albany has a population of 25,000 and is 400km from Perth airport with very little in between.

There is no way that the demand for one-way hires from Albany to Perth is ever going to come remotely near that of the opposite direction. So they have to charge a fee, in state with the highest labour costs in one of the world's most expensive countries.