I'd answer all of the above and then some.
I think most of the time it's parents, teachers, and community pushing against national and local government structures and academy trusts for academies. Schools are being asked to do everything to fix all social problems children and their families (and sometimes employers and the justice system) face on a shoestring and a prayer, while also being agile enough to change at the whims of the powers around them. Teachers should be cut some slack, though I don't think that includes ignoring clearly unprofessional behaviour. I have had a word with a couple teachers around this, thankfully that was enough to ensure appropriate apologies and no further issues.
For many teachers, that also includes the whims SLT. Sometimes those whims are coming from pressure and whims of the LA or academy trust, sometimes it's their own ideals that develop from unrealistic expectations. SLT often, to get into that job, have a particular attitude towards work that isn't healthy, IME, and sometimes don't get that it isn't sustainable nor is it a moral failing to not be doing 10-12 hour days all the time. It's true of many similar professions.
I've been the worried/active parent, I've been part of parent consolations, used to go to every parent event (stopped last year when it was a 5 minute meeting with form tutors, when it takes me an hour to get to the school), been a parent governor for years, was the first one to actually challenge a policy to make it go to vote/rewrites because it was horribly inconsistent and clearly copied over from multiple other policies, but never edited to be one coherent document and I still view us as largely powerless to change the system as parents. Schools have so many other metrics they're measured by, anything any individual parent is saying is a whisper in the storm. The time there is a big part of the life of the child, but they'll leave and the school moves on.
I've two kids out of school and two more getting close, and I'm still not sure what parents who aren't spreading shite on social media and have children who are behaving and happy to learn can do that would improve things for teachers as parents. Even working within wider consultation and connected areas can feel pointless, either due to the lack of resources to do anything or the whims of a headteacher / trust lead / government official.
I don't think it's helped when it's framed as all parents or all teachers. Some in any group like that can be great and some are assholes who have an antagonistic view towards others. I've sat in meetings with the head of Education Welfare where I am and heard her infer parents are dim and openly call parents who contacted the LA for help arrogant, even quoting from emails of parents asking for help to somehow support that I can see why parents might think falls under Education Welfare, but sadly doesn't (mostly to do with children with additional needs). Things like that are part of why I stepped away from being so active in schools - it's so draining and when you run into those that are antagonistic but powerful, it does make you feel like what's the point & carry on supporting just your own kids at home.