I could be wrong, but I'd imagine that on a day to day basis, very few teachers in that school actually give out demerits for kids scratching their hand etc. Once the behaviour is good, those rules are probably just there in case kids are taking the piss (everyone dropping their pen at the same time etc.)
My school in Ireland was very strict, but most of the time rules didn't really need to be enforced with punishments. I only ever got 2 detentions for chatting in class and they didn't even tell my Mam, so she thinks I got none, haha!
I personally wouldn't want to work in a school where kids can't even talk on the corridor, but I have noticed sometimes behaviour over here is all or nothing. If you give an inch behaviour bubbles up extremely quickly. I don't remember this being an issue in my Irish school and other members of staff from other countries have commented on it as well. I've only ever taught in London (in a range of schools types/ areas/ demographics) and from what I have seen there are major issues with behaviour (especially low level disruption) across the board. Parents don't seem to want to tackle this, or allow teachers to tackle it.
I think the standard of teaching over here is much better than in Ireland, but Ireland still comes out much higher internationally; I suspect this is to do with behaviour and attitudes towards school and teachers. It is much easier to learn without constant distractions and interruptions.