I have never killed a snake. Around here we have prairie rattlers, and although the state does not recognize them as native, there is a lake a few miles away that has water moccasins.
Both my husband and I agree, that only if someone gets bit, we would first try to "box" the snake, but if it could not be boxed without other bites we (he) would kill it. The only reason we would do that is that for many types of anti-venom it is best to have the snake for ID purposes.
Any other time snakes are relocated. A lot of people we know kill them just for the sake of killing something, so if we see one around these people, we will relocate.
We also stop the car for any snake in the road, I keep a long stick (4-5ft long dried willow branch) in both of our cars, so in the event it is something other than a bull, or garter (the 2 we see all the time) we can use the stick to help move the snake out of harm’s way.

But in my “yard” we hardly ever find anything, only little garters, we pick them up and show them to our little girl, and tell her that they are a “good” snake, that if she sees them it’s ok. We have a SD herp book, and show her the ones that are “ok” and the ones to stay away from.