Empathy for whom the mother or the child? Mature parents do not slap their children across the face for acting up. They take the kid out of the store until they calm down. If this happens in public, one can only imagine what goes on in private. If I had seen it, I would have snapped a picture of the three of them, as well as the license plate of the mother's car. Then I would report the woman to child protective services so they could investigate.
The group sprang into action on Sunday morning atop a Brooklyn subway platform when they heard the young woman screech for help as the heavy-set man bear hugged her from behind and propelled her forward.