You're failing to differentiate between beating and spanking. A beating is when the adult is out of control with anger and takes it out on the child, often physicall injuring the child. I agree that there is absolutely no excuse for that.
A spanking is reserved for punishment for a specified infraction. In our case, we give the child the option to change their behaviour forst with words and other types of reinforcement. If the child continues to rebel, it escalates to a spanking. Usually one whack, and most often not with much momentum. (per #30, I tried it out on myself first to note the amount of pain produced. It took a lot to make it hurt. It would take absolute abuse to bruise or draw blood)
The other reason for a spank is to reinforce safety. If a child continually runs into the street and telling him to spop doesn't work, a loving parent will reinforce those words with a small amount of pain.
Using a specific, purpose built object, instead of a hand allows the child to fear the object rather than the parent.
Still care to turn me in to the socialist workers?