FWIW, as a science teacher, behaviour in corridors is a safety issue, particularly for our science technicians who have to move equipment between classes during changeover times/break times.
Distracted kids not looking where they are going can cause accidents.I don't think that means corridors need to be 100% silent, but a certain level of behaviour is required. Corridors aren't the place for letting off steam between lessons.
I honestly think a lot of parents have no idea what behaviour is like in the average state school today- I think they would be shocked at how much behaviour which was totally unacceptable when I was at school about 10 years ago is pretty commonplace now.
As a final point, there are a few kids I teach who display pretty extreme behaviour as a result of unmet SEN needs. However, as a classroom teacher with 32 other children to teach, some of these needs are beyond my ability to meet. These pupils need proper assessment and support, which costs money which schools don't have- I wish we had the funding to support all SEN children really well but this is not the case.
The resulting behaviour is extreme to the point of sometimes being scary- I know it upsets other children in the class. And sometimes, those children are seeing frightening behaviour on a daily basis.
I had a Y11 kid commit a really violent assault in my class just before half term- regardless of his needs, that impacts everybody in the room. IMO, the sanction he was given wasn't adequate. If he'd done similar in a pub (for example) he'd have been arrested.
There's a combination needed of a really robust behaviour policies in schools, with supportive and present SLT, as well as more funding to properly support children with SEN and difficult home lives.