Got to challenge the words "raiding" or "poaching" in this context. They imply taking something that belongs to someone else. Instructors don't "belong" to the flight schools. Didn't you fight a civil war in the States over that?? Instructors have worked and studied hard and handed over their own cash, lots of it, to gain their qualifications. They are both legally and morally entitled to get the best return they can on that.