They are paying Australia's GST. The tax you are referring to is income tax. They are exporting a product to another country and paying income tax in the country where they are producing the product.
Companies have to pay value added tax in the country they are selling their goods and services in, but their income tax is paid in the country where they are based.
Companies have to pay value added tax in the country they are selling their goods and services in, but their income tax is paid in the country where they are based.