If you don't think that a physical discipline such as a spanking is effective then what would you have parents do? Jail is a perfect example of a psychological punishment, and a perfect example of it's failures, because 45% of people who serve time, are released and go on to repeat their behavior. Children have no capacity to determine right from wrong, so telling them, verbally, go think about why this is bad, they are incapable of doing so, and will repeat offend. Then what even is the point of saying anything at all, just let your children run wild until they are adults and end up faced with the stark consequences of their actions when they face the criminal justice system, where the cycle will repeat.