An anecdote from a previous job. (fairly long ish)
I worked at a school where some of the pupils vandalised the toilets on a regular basis so whole locking of the toilets was done, pupils had to ask the teacher then sign the key in and out from reception (as above).
Many parents complained about this (more than those that complained about the toilets being out of use due to vandalism), the school reopened the toilets and employed a new member of staff (on a temporary basis).
The new job was to patrol the corridors and prevent the toilets being damaged (also collecting of pupils who where out of lessons). Again parental complaints this time about the school wasting money on a "silly" job.
During the school summer break the toilets where gutted, open plan, stalls in both boys and girls toilets, all doors, sinks and facilities viewable from the corridor. (not the inside of the stalls). Cameras went up outside the toilets and looked in to the room (but not the stalls).
Again parents complained about the waste of money (rebuilding the toilets), lack of privacy due to being open plan (floor to ceiling stalls no-one could see in) and finally the cameras.
Within one day of being back the toilets where vandalised. The vandals caught on camera and those that vandalised the toilets had a fixed term exclusion and their parents billed for the damage.
at every turn the school was argued with by various parents, but after the first exclusion there where no more incidents.