[objclxt]

Advertised prices in $ exclude sales tax, because for most states it isn't levied on digital downloads.

However, VAT in EU countries (don't know about Australia) is included in the price. This causes a fairly substantial discrepancy, as VAT can be rather high (in the UK, 20%). Other discrepancies can usually be put down to exchange rate fluctuations, which with the recent financial issues in Europe have been somewhat unstable.

[neotek]

Regarding Australia, our GST is a flat 10%, and the AUD is near parity with the USD (and has been above parity for most of the last 12 months). The price discrepancy is far greater than it should be if those were the only factors.

The Australian Competition and Consumer Commission, an independant regulatory body in Australia that oversees the Trade Practices Act (among other things), is in the process of inquiring into the so-called "Australia Tax" to find out why companies like Apple and Valve charge far more for software sold in Australia than in other countries despite the low true cost difference.

[inopinatus]

The ACCC is pissing in the wind. It's just a matter of geographic price segmentation to maximise revenue. End of story.

Also, end of legal challenge:

* there's no violation of free trade agreements, which are about governments dropping barriers like tariffs and quotas and confer neither rights to individuals nor obligations on businesses, and

* there's no violation of individual rights, because country-of-residence is not a protected class, unlike gender/orientation/skin colour/race/disability.

[cube13]

Prices for non-Valve developed and published games are also determined by the individual publishers.

Unfortunately, that means that the real reason is "Because they can".