Actually most of the deaths of Native Americans and Aboriginals happened incidently through diseases spread by newcomers that they had no immunity to, relatively little effort was involved.
Are you calling all those pioneers and settlers lazy? I mean they did try to annihilate the natives, what with all the poisoned wells, tainted flour, hunting parties and what not. Is it their fault that smallpox was so much better at killing? Ahh good old British Imperialism, those were the days!