Use the Lefties’ weapon against them. Sue the administrators personally and the school corporately for emotional distress caused by abuse of power. Even if the suit does not succeed, the threat of being sued and having to defend themselves might push the head-honchos to send their underlings to reeducation camps to learn how to use discretion when implmenting “zero tolerance”—zero tolerance without intelligent implementation becomes abusive. But, of course, that would cost the parents time and money. It’s a shame that even turning the Lefties’ weapon against them can only be done at great cost and expense to the victims.
Discretion and zero tolerance are mutually exclusive.
The schools tell the teachers/administrators that they won't back them up if they don't enforce zero tolerance and DO use their own discretion, so the teachers err on the "safe" side of being absolutely stupid.