One day last year, a citizen on a prairie path in the Chicago suburb of Elmhurst came upon a teen boy chopping wood. Not a body. Just some already-fallen branches. Nonetheless, the onlooker called the cops. Officers interrogated the boy, who said he was trying to build a fort for himself and his friends. A local news site reports the police then "took the tools for safekeeping to be returned to the boy's parents." Elsewhere in America, preschoolers at the Learning Collaborative in Charlotte, North Carolina, were thrilled to receive a set of gently used playground equipment. But the kids...