Have you noticed how many countries around the world are building security fences? There is a near mania to build walls separating nations from neighbors who threaten them with illegal immigration, crime, poverty and terrorism. Some of the largest countries in the world are building them. Some of the smallest countries in the world are building them. Some of the richest countries in the world are building them. And some of the poorest countries in the world are building them. It seems security fences are for everyone – except the very richest, most powerful nation in the world. Recently, for...