They lied
Some kids react better to the threat of a paddle. I know we sure did. We all wore safety glasses in shop, even the kids who didn't care if they passed because the penalty was a lick in front of the whole class. And Coach Page used to play for the Dolphins.
They were as wrong as the others who told us that corporal punishment would solve the same problems.
You should have the right to send your children to schools where physical punishment is allowed. And I should have the same right to send my children to a school where my children are not touched physically, except by me. Since government schools are mandatory for those who do not have the resources to educate them privately it is a good thing that government employees are not given the right to touch children for purposes of "punishment".