I will give you an answer for the why? Simple...there is never only one, it will keep coming back which means more opportunity for it to find a weak spot and the way coons populate you could trap 50 and there will still be plenty to go around. I know this from experience having spent many nights shooting them for a friend...they just kept coming and killing. They went as far as to rip away piece of board to squeeze in, chewing through and ripping apart wire, latches must be coon proof because they have the dexterity of a human and can open latches with amazing speed and they are strong determined blood thirsty critters They destroy food stores and many of them carry rabies not to mention the external pests. For rodent control there are snakes, cats, bobcats, fox and even coyotes to name a few and traps for rodents so the coons are not irreplaceable if 100 were taken because they are too far removed from endangered.
I think those are enough reasons for trapping it...if you think I need more reasons, I can post plenty of pictures of their destruction to both coops and chickens. By the way...I stopped counting at 36 I killed for her and she had trapped at least 20 herself. While I am an animal lover, my chickens are mine not a meal for predators and this woman will shoot.