I certainly think there are valid reason to kill animals and valid reasons not to.
Here in Oregon, one is
encouraged to kill bullfrogs by wildlife conservation officials. It is open season on them year 'round for hunting/jigging whatever it is called for people who eat them. Ditto for AZ, CA, British Columbia, Hawaii and they are also a problem in many other countries. Tax dollars are spent on bullfrog control efforts in the Western US and Canada. There really isn't anything else to do with them here but kill them or lose all of our native frogs and turtles.
Cute little red eared sliders are also a problem in the Western US for native turtles and wildlife agencies are trying to cope with them too. People release them into any body of water they see and think it is ok. It isn't.
I do mention Bullfrogs being a problem on various message boards because I've read dozens of threads where ponders are shipping eggs and tadpoles across the country or buying them online from suppliers who should know better but don't. Not giving a rip whether or not they could be causing environmental harm. Every little bit helps. Herons can transfer eggs or even adults to wild bodies of water spreading them to areas that may not have them yet. We ponders should be aware that some of our beloved pond pets aren't so beloved everywhere.
However, If I lived in any part of the US where they were native, I would not kill any bullfrogs that showed up in my pond. If they started eating my fish, I'd relocate but I would not kill them. There is no reason to and nothing wrong with relocating.
Many snakes
are endangered or threatened. From habitat loss and because many people kill them on sight because they hate them or fear them. Many people probably get bit by poisonous snakes trying to kill them than if they would just leave them alone in the first place. You have to get pretty dang close to shovel them or whack them with anything....scary.
Again, I know you can't change anyone's mind.
I have friends I've known most of my life who are afraid of spiders (but who love snakes) and who jump up and scream in public if they see one. I think it is ridiculous. They say they can't help it. Then they call me and want to know what bug spray to use in their yard because their plants are all chewed up. They send their boyfriends out to smash all the big garden spiders and then would rather use chemicals....