It has nothing to do with children being unruly and everything to do with protecting them. Leashes are used in situations where there is a danger to them that they don't understand and they provide extra security. Places with high traffic, public areas where they could become distracted and lost, places where there is the chance of an abduction. It provides extra security for them and you. Once they understand the reason for the leash most of them do not mind but in fact find it comforting as well. After all the leash means that you are attached to them as well. What child does not find it comforting to know that their parents are not going anywhere?