I don't have statistics, but one wonders about the effectiveness of gates and guards when a mass murderer shows up.
And who remembers when colleges and universities were free? Zero harm came from students even during Vietnam protests, IIRC, except from National Guard and mad snipers.
IMO, mass surveillance is not the answer for "safety". It is the lazy way out, similar to bombing civilians and destroying their life support infrastructure instead of fighting "bad guy" COMBATANTS.
We live in an age not of delicate and selective fly-fishing, but one of dynamiting lakes to gather stunned and dead fish.
Chances of data being used for political repression are extreme, if not by schools but by threats, warrants and subpoenas. And what are the chances? We have already passed that point.
"We have seen the enemy, and he is us." ... Pogo.
Damn mass surveillance.
Why not skin color at this point. If people don't see the problem with these systems at this point, not sure what to tell you.