[markc]

I'm not in the camp of saying all corporal punishment is abuse, but IMO it's quite limited in the ages and situations where it's applicable.

Has everyone on this thread forgotten about non-physical punishments?

These should take the form of natural and logical consequences whenever possible.

Make sure the kid understands what's expected of them, and how they failed to meet the expectations. Then, if needed, reinforce this with natural consequences (when it makes sense). Classic example is taking away possessions or privileges when they're misused.

Punishments can certainly be arbitrary or disproportionate (which tends to spark resentment - and possibly the mental baggage you mention) so it's important to do it thoughtfully. Done right, it's effective and non-traumatizing.