First, my experiences are much more mixed than yours are. I occasionally run into someone who brags about killing snakes, but I don't always get that reaction from people who aren't snake keepers. My team leader at work often gets little snakes caught in his pool filter. He just tosses them over the fence into the woods. I've heard of other people who are glad to have non-poisonous snakes in the barn but don't like them near the house. I've also run into many people who don't pay attention one way or the other.
Secondly, I think that much of how one feels about snakes depends on how one is raised. Some people grow up around adults who are afraid of snakes and kill them at every opportunity. They've learned to fear snakes and to kill them. Other people may not care for themselves, but they haven't taught their children not to fear snakes. Because their kids are afraid, they kill snakes around the yard because it makes their kids feel better. When I was a kid, my dad often brought little reptiles home for me to see. He emphasized not picking up anything that I couldn't identify, but as far back as I can remember, I can remember hearing, "Be gentle; Don't squeeze it; It won't hurt you, but don't scare it; No, let's just let it go; It'll be happier in the woods." Of course, in today's over-regulated world, Dad would probably be fined by some governmental agency for bringing animals home for me to see.
I think many people who don't pay that much attention will talk about killing snakes just to upset people who like snakes. I've had people start down that road with me and then admit that they were just kidding when I didn't react strongly to what they were saying.
I think we have to reach a careful balance. In many states, it's illegal to pick up a native snake without a license. When those laws are enforced, particularly against curious people who are just mildly curious, a snake becomes associated with a negative interaction with regulatory power. Once that association is formed, those people aren't going to care about snakes being killed. Likewise, we need to be informative without being preachy. Yes, snakes are very beneficial, but there are so many things crying for our attention these days that no one wants to be the target of one more rant.
Bill
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It's not how many snakes you have. It's how happy and healthy you can keep them.