I do not think that kids should be trained like pets. They are more intelligent and react to a more nuanced approach. My point about punishment just means that bad actions should be sanctioned and good actions rewarded.

My parents never physically punished me, but as soon as I was old enough to understand what was going on, just knowing that I'd disappointed them would make me feel extremely bad. There's no resentment there. They taught me how to behave in a way that is acceptable in society and if I misbehaved I was aware that I was wrong. Hopefully that's how everything would go.

But as always, there will be bad apples (and good ones, too). What do you do when someone's such a sociopath that they don't care when they hurt other people? That's when I believe that punishment should be carried on by the society and not the parents, in the form of jail, probation, juvenile court, etc.