"Only England was able to totally exterminate an entire race/tribe of people right down to the last female, and they were the Tasmanians."

Not so Donuel, England, or more correctly the British Government had very little to do with it. Those hardy sons of the soil, those intrepid pioneers, mostly land hungry settlers and ex-convicts, on the other hand did have something to do with it in large measure. They more or less governed themselves and did pretty much what they wanted to, with little or no interference from London.