Well, the whole thing depends on exactly where the cameras are situated.
If they're just pointing towards a row of sinks and a paper towel dispenser, all is good.
If, however, they're pointing at a row of urinals or within any of the cubicles, something's wrong.
I would assume though, from the reason the camera(s) were installed, they are only recording acceptable viewing areas.
However, once the Press get hold of a headline like 'CCTV within children's toilet' they won't let it go, will they?
CCTV is a good deterrent. It has also caught images of murderers and suicide bombers apart from eight-year-olds chucking soap down the loo.
The UK has the most CCTV systems of anywhere within the world.
Some will see this as an invasion of privacy, others as an aid to preventing/solving crime.
I mentioned my experience of CCTV merely as an interesting anecdote, hopefully.
If the head teacher in this instance has stopped the lovable little gits from choking the karzis up with bars of soap and great big wads of paper towels, he's probably saved himself money by not having to pay plumbers.