I don’t think those teachers who choose to paddle are, as a group either cruel or excessively punitive. Many do believe it is an ‘aid’ in the toolbox of interventions. It has the theoretical advantages of being over quickly, so less disruptive of class and social relationships, and unambiguous.
Noncorporal punishments are in theory no less painful, even if the pain is psychological and the punishment ( as in Saturday school or ISS) lengthy, or lines (boring), or chores(demeaning) . Unfortunately there always are a few bad apples, and, of course, the existence of cp does allow those with an obsession with it to work under a cloak of legitimacy. . Therefore it is imperfect as a discipline system, but that doesn’t mean that it cannot be effective and moderate But my worry about this is that it is too easy to hijack by those who either abuse it for its own or their own sake.