A slap on the hand is just not enough to stop bad behavior. Sure, it will pause it momentarily, eyes will well up with tears and promises of different behavior might even be made. There will be no positive long term results as the punishment is almost non existent.
The disobedient one keeps claiming good intentions, but these good intentions don't cause good results. Would a bank robber be forgiven if he claimed good intentions for his crime? And, if he repeated the offense over and over again, would he always be given a second chance? Should he be given one? And, if by some chance he is released and commits the crime again, the system that gave him the freedom to repeat the activity is guilty as well.
The person that delivers the little slap doesn't want the bad behavior to discontinue. In fact, that person probably gains from these misdeeds. Otherwise, the repercussions would be more severe and the behavior would be terminated.