As far as games are concerned, like from a service like Steam, I imagine there is an element of industry control in the works. It could be very economically damaging for Australian companies, or branches of companies, to still have to deal with imports while Steam can knock down the price tremendously at no cost.
Steam is no stranger to the idea that lower prices bring your market to more people and your total profits come out better much for the efforts. That's why they have massive 75% sales, and the numbers to back up them continuing to do it. With that in mind, I think it is pretty unreasonable to suggest that Steam is keeping it up just because they think it will get them more money - they've outright proved that wrong, in some ways.