Because they're wild rodents and that would just be icky. And I don't really need to catch wild rodents to feed my snakes. But a captive bred and born rodent that's escaped from its cage in my house and later caught in my house? Why not? Why kill an animal needlessly and just throw it in the trash? It's a waste of a life. I just think you're going overboard in your quest to keep your snakes safe.