Because they are snakes!!!! They have a useful purpose granted, but so does much of the animal kingdom. Spiders do not bother me in the least, but for everyone of the girls here they do, so I kill them because they scare them. It is the same thing with porcupines and skunks, they serve a purpose too, but they are just not worth it to have around when I have to pull quills or clean my dog because of them...best to send them down the .410 highway. It all depends on a persons fear factor. I HATE snakes so I kill everyone I can, but others like yourself are not bothered by them. Me, I will climb 450 feet in the air, while some people like my mother can not reach the second step on a ladder. All snakes are lethal to me...because they could give me a heart attack upon seeing them!