The absolutely essential aspect of these stories is complete, unbroken, total genre-blindness of all characters. If they, even momentarily, realize that their small town actually has a shockingly high murder rate, the effect is ruined. In an urban crime show like Law&Order or whatever, the cops can go to anybody on the street and say "We're investigating the murder of Jackknife Bob" and the witness is just like, "He got whacked? Oh well, I didn't do it."
But in a Small Town Murder, it is absolutely imperative that everyone the detectives talked to is shocked that such a thing could happen! "Dear me, a murder? Right here in Shirefordtonstead? Good heavens!"
Ma'am, it is season seven. You are the fifth proprietress of this quaint antique shop. The first three were murdered, and the fourth was the killer. In the normal, rational world, living among this high a murder rate would have a profound, dare I say traumatizing, effect on your worldview and your perception of your own safety. But you are not of the normal, rational world. Your unshakable and clearly counterfactual belief in the safety and stability in your surroundings is built into your character. And for this I love you. Never, ever change, Tiny Quaint Friendly Villages Full of Constant Murder.