User blog comment:DYBAD/Character Sheet/@comment-4867780-20141016085735/@comment-26241075-20141016112254

Orks being hunted down is not really the right word, those guys don't even know what death is, so running away is not something they would do. Hell, in retribution, they fought each others when under Exterminatus.

And about the Eldars, you are right, they're tactical, so I hardly think they can start a fight they know they can't win, and ambush makes no sense to them as they can predict the future.