So many schools only do a cursory check into a teacher's background; or listen to students when they make initial reports of predation. These ARE things schools and districts can do; they just opt not to deal with these internal issues until they hit boiling point.
The wacko's with guns, bombs, etc., even on total lock down you'd be hard pressed to "deal" with these effectively.
background checks aren't even all that efficient. Tons of crimnals have yet to be caught, some had records expunged, some are minors sitting next to your child in the classroom, some background checks aren't national or international...the list goes on.
