Amazon's media stores are all but nonexistent outside the US, and the Fire is sold at cost with the expectation they'll recoup on media sales, so it's not surprising they haven't released it elsewhere. Google's non-US media stores are pretty bad too.
Amazon Fire is available in Australia I know that much.
And why compare yourself against Amazon when Apple is rumored to be launching an iPad Mini which will be sold in 30+ countries almost immediately after launch.
There's available and "available". I have do doubt there are at least a few importers who buy Kindle Fires in the US and are selling them in Australia, but that's not the same as the Kindle Fire truly being available in Australia (the way the Nexus 7 is). Unlike other Kindles, Amazon will refuse to ship a Kindle Fire to Australia. I think that's a pretty clear statement from Amazon on Australian availability.
That's still much better than the Amazon Fire which AFAIK isn't even sold outside of the US.
See also this article from The Verge: http://www.theverge.com/2012/6/28/3122716/nexus-7-internatio... ("The Nexus 7's most important price is £159, not $199").