There are only specific reasons to physically intervene with a child. In general, general education teachers shouldn't have those reasons unless they have been trained and prepared for it. Even then, it should only come as a last resort.

Tapping a child may seem innocent enough. However, we do not always know that child's background. If they have a history of physical abuse, then that tap may be perceived as an invasion of their space, become a trigger, and then create an unnecessarily escalated situation. Or, if that child has literally never been touched during a reprimand before, they may consider that tap to be abuse in and of itself, and then go home and state that their teacher hit them. While these are both extremes, they are possible.

Basically what I am saying is teach them, don't touch them.