As coporal punishment in familes is more between parents and child than anything else, I will share my opinion form this perspective. Any form of punishment that is carried out, should help to correct the behaviour of the person. However, there are times where parents might cane their child out of anger. The pain that these childern feel, might make them resent their parenrs even more and perhaps even encourage disobedient behaviour. They many other ways to discipline a child without using physical force. For example, we can warn the child sternly about the consequences of their actions and maybe perhaps give them less pocket money if they fail to correct their behaviour.
To get a result from children and teenagers, you need to force them. Then purpose of corporal punishment or any other kind of punishment is to make them remember the mistakes they have made. How will they know their mistakes if we don't use effective ways? Like they say, "There is no answer to the question that isn't answered." If there isn't practicality, there won't be a result. Let me give you an analogy: How can you speed up a car if you don't press the gas pedal? The same thing in this case. How are you to make a child correct their mistake if you don't use an effective way to make them remember? That is the esscence of corporal punishment. Also, it is the families' choice, not the person who bans it. Families should have the rights to choose how to punish their own children.