I am playing devil's advocate here but perhaps the English deserve some blame here, because it does seem that blame is inherent in this topic. They started it with their social darwinism. It began with the English ruling class in their manor houses, living off the proceeds of their plantations made profitable of the back of black slaves.
Then of course the English decided to get rid of predominantly Irish riff raff by sending them to Australia for stealings loaves of bread because they were starving and where the British then had to deal with the natives. The English then pretended that the natives weren't organised or intelligent enough to own land and declared Terra Nullius. As well as displacing the Aboriginals, declaring Terra Nullius denied the existance of Aboriginal Law - the Crown became sovereign. At this point the traditional lifestyle of the Aboriginal people was doomed. They were no longer allowed to follow their traditional tracks because of the newly imposed titles. Its quite convenient for the English to support the push for an Australian Republic and wash their hands of history.
Anyway social darwinism continued well into the 20th century (Australia was still little England until well after world war II) facilitating a climate where such policies could amazingly be implemented and supported by law.