We had security theater in the burbs, in fact we probably had more and better guards and metal detectors. The big difference I see as an older parent is police involvement, at the good schools the cops occasionally lay down the law on loitering, possession, occasional fist fight requiring no medical treatment. The bad schools are full of daily police calls for all of the above plus stabbings, graffiti, handgun possession, rape, hospitalized beatings. It seems the biggest danger at the good schools is boredom and rebellion, and at the bad schools the biggest problem is physical danger.