I mean, it could be a push to get rid of a SLT certain members of staff don't like; or it could be that teachers have genuinely had enough of bad behaviour.
I think one of the problems is that what was seen as discipline in the 80s and 90s (and I don't mean the cane) is seen as too harsh nowdays. Both too much and too little is expected of children. They are not mini adults. Their opinions are not of equal value to an adult's, because most of them have no ability to even imagine consequences. Children are encouraged to question teachers without it being taught that there is a time, place and a way of expressing your opinion or questioning someone elses. And that, sometimes, you just do what you're told without answering back or questioning. It's like they have lost the ability to judge people and situations and behave accordingly. There's no fear of teachers, so there's no reason to do what they ask. It would have been seen as unbearably humiliating to be shouted at by a teacher when I was at school. Now I go to pick up DS and I can hear teachers and SLT BELLOWING all over the school and kids still running riot. There are no punishments for the bullies; there's rarely support for teachers who just need a principal to stand in the room and say this behaviour isn't good enough and they expect more.
We should also devolve responsibility to individual schools and teachers. They know their area; they know their kids and they know the style of teaching that works. They should be allowed to do that rather than every kid learning exactly the same thing, in the same way, at the same time and all being taught to pass exams rather than actually become educated.
Another problem is that some people will push and push and push until they can't go any further. You have to set expectations from nursery/reception and carry them on throughout education. Schools need to actually have reasonable discipline policies, enforce them fairly and tell parents when a severe issue has occurred. If you let a kid get away with being constantly being rude in class, it will grow into them trying more and more things (throwing paper aeroplanes, which become chairs, which becomes turning over tables and punching other pupils and staff) to find out where the limit is. (And the problem isn't just schools, it's that there seem to be a shocking number of people who either don't know how to parent or can't be bothered to parent. There are loads of shittily behaved middle class kids in DS's class. Their parents are lovely...they also want to be their child's best friend or, frankly, are too tired to actively parent, so choose the easy option of letting their kid do whatever they want. They then question sadly why their kid behaves the way they do or, worse, they don't even recognise the kid's behavious as completely unacceptable.)