Without starting a firestorm my impression was a lot of this stemmed from a certain event in the late 80's meaning a large group of largely pizzed off Aussies ended up overseas largely not through their own doing.
They did come from a culture where they had been told they were the best, our system was the safest etc.
The "second wave" (including me) in the wake of Ansett certainly had it's share of people who fit the above, but we also had to contend with a lot of pre-conceptions from the first group.
I think it's improving as the new generation move in who aren't associated with either of these two groups.