First, it's worth noting that US prices don't include sales tax. Australian prices include a 10% GST.
Second, international companies will end up doing their accounting in one currency. For tech companies unsurprisingly this is US dollars. Transactions in foreign currencies get converted to USD. Companies hedge themselves against FX risk by locking in exchange rates and giving themselves a buffer so they don't need to change prices every day. Ergo, things in foreign currencies will always cost a little bit more.
So if a Macbook Air costs US$999 and A$1099 (hypothetical, the Apple store is down so I can't check what the actual price is) then that's about right (given A$1 = ~US$1.04).
That all being said, high prices in Australia largely come from it being a small market and, more importantly, consumers putting up with it.
Books are the worst example of this. UK companies get the distribution rights for Australia. Australian copyright law largely protects them from imports (although this was relaxed by the previous Howard government in a 1am Senate vote). Yet what costs $10 in the US will cost $25 in Australia.
The Dell E6x00 laptops routinely cost The "waterbed effect" seems to play a part too. The US is a large single market so has a lot of purchasing power compared to pretty much any other market. I've thought that cameras are cheaper in the US (than Europe or Australia) for this reason more than anything else.
To give an Australian corollary to this: Dan Murphy, the largest alcohol retailer owned by one of the two supermarket conglomerates (Woolworths), is killing smaller competitors because their purchasing power is so large they can often sell things (at a profit) for less than non-chain stores can buy them wholesale.
For software in the era of digital distribution there's no justification for Adobe's prices here. It's the same software in the same language. Perhaps they needed different TOS/EULAs for Australia (or at least have them reviewed to make sure they are compliant with Australian law). That's about it.
One thing to be thankful for is the ACCC in Australia actually has teeth and through the Trade Practices Act and Corporations Act has a lot of power. The FTC in comparison seems to be a partisan paper tiger in comparison.