Nope, you're just unlucky. The US is a different region from Australia.
They do share the same language, though, so a Pokemon from the US and a Pokemon from Australia will not work for the Masuda Method. --- YOU WANT SOME FUNERAL TO GO WITH THAT CAKE? | 3DS FC: 3437 - 4335 - 3104 | | Friend Safari: Panpour, Wartortle, Frogadier |
Technically, language is the sole determinant of whether the Masuda method can work or not. Somebody in Los Angeles could very well register United States/California for their location and Spanish for their Pokémon's language--and may have imported their pre-sixth-generation Spanish-language games from a Latin American country. Likewise, Canada/Quebec could very damn well register French on the GTS ever since Diamond/Pearl. And don't get me started on Switzerland (could be German, French, or Italian) or Belgium (pretty equal odds of French or Dutch)... --- I am a die hard Pokemon fan to the most, including the traditional hate of Yu-Gi-Oh.