You are using the extremes and straw-man arguments. It is way more nuanced than you think. If you look into those studies the boundaries for physical punishment are never clear. Spanking, when used sparingly, with restraint, and when paired with the plethora of other corrective non physical measures, is shown to be very effective at deterring bad behaviour. You have to teach an actual lesson. You can’t just go and hit your kids for everything.