We don't actually know the whole story in this situation. The girl her parents and the school should work together to stop this happening. Not run to the papers and demand an unmanageable toilet free for all.
For all we know the girls using toilet paper for sanitary protection.
Nice bit of victim blaming there. 
I think you find that the reason her parents went to the papers was because this is the second time it has happened. They worked with the school after the first time but the school still refused to let the DD go to the toilet again.
Also blaming the DD because she may have been using toilet roll instead of sanitary protection is just wrong, maybe she came on completely unexpectedly as often happens when DD's first have periods (and also may still happen even if they have been having periods for a while).
And No I don't know what the answer is for schools with badly behaved DC but I would hope that they would let DD's go to the toilet if they are not known to be trouble makers or skivvers, and take a judgement call if the trouble makers or skivvers say they are desperate. With a view to making them wait if they just go out and mess the toilets up after the first time.
Weetabix
Your objection to toilet passes makes no sense either. If your daughter leaves the classroom to go to the toilet does she ask permission first or are they just allowed to leave? Either way the teacher and all her classmates realise where she's going so what difference would showing a toilet pass make?
Absolutely I agree but in a young DD's head the other DC don't absolutely know where they are going if they speak quietly to the teacher and pop out and come back quietly. I'm sure they will guess though Whereas if they have to wave a toilet pass everyone knows where you are going.
Surely, if you have within a school, a SERIOUS problem of kids misusing the toilets and avoiding lessons, ... so serious that it is genuinely worth forcing kids to piss themselves or bleed through clothing... then you have a FAR bigger problem and the school is really failing quite dramatically.
^ ^
This