It is also illegal in Canada (similarly with stories), some US states, some European countries, and England, Wales and Northern Ireland (though only drawings rather than stories as far as I know).
I think such laws are hideous.
Also note that in Australia "supreme court" does not mean that its rulings determine federal common law, that rests with the High Court of Australia (the next court up)[1]. So on paper, other States could have different laws on the topic (but I haven't checked whether the case was appealed to the High Court).
Ah, you're right (I didn't read the whole document). In case you're interested, in other states there is a different criminal code (called the Crimes Act (1990) in NSW)[1]. The section on "child abuse material" (15A) is quite vague on what limits there are for something being "material depicting child abuse" and there is also a catch-all statement saying that something is also considered child abuse material based on " the standards of morality, decency and propriety generally accepted by reasonable adults".
In general I would be surprised if it was legal in any state. I also checked, and it's considered "objectionable material" in New Zeland[2].
[1]: https://www.legislation.nsw.gov.au/inforce/a0a6239c-5e99-6ad... [2]: http://www.legislation.govt.nz/act/public/1993/0094/latest/w...
I'm not agreeing or disagreeing with whether it causes actual child sexual abuse, it's just something to consider.
http://articles.latimes.com/2007/nov/09/world/fg-autopsy9
Further, sex crimes are...different everywhere.
https://www.japantimes.co.jp/community/2014/12/08/voices/for...
From a sociology standpoint you need to be careful when doing cross country comparisons. But, reported statistics are not simply accepted at face value.