Unless of exceptional ability or a technical or scientific researcher, one must contribute significantly to gain Australasian citizenship.
For instance, were an American to steal high-tech weapon information from the United States, they could obtain Australasian citizenship.
Of course, such a possibility is slim since, at present, the United States is not vastly superior to Australasia in any military technology areas.
Until it recruited European scientists and technicians, American technology was at best on par with the major powers, and even lagged behind older powers, such as Britain, Germany, and France in many aspects.
In 1913, Australasia's economic development was also rapid. The substantial population growth was one factor, second only to the ongoing infrastructure projects within Australasia and the operational commencement of the Leonora Industrial Base.