There are only 18 million Australians living on an entire continent that they do not share with the United States. Consequently the Australians cannot afford the suicidal multiculturalism that plagues us.
On 25 September 2006 at 08:45:00 (Canberra time), the resident population of Australia is projected to be:
20,668,670
http://www.abs.gov.au/ausstats/abs@.nsf/web+pages/statistics?opendocument
They could also have hostile neighbors.