I've not read all the posts but went to school myself during 80s-90s and teacher of 18 years, secondary.
Now teachers work harder than the kids. No accountability for the lazy child not pulling their weight. Why has little Charlie not got their target of a 7? Because he does f all in the lessons and no revision.
Parents take the side of their offspring even if the evidence of their offsprings poor behaviour is irrefutable. Parents are generally unsupportive and believe that we are social workers, mentors, youth workers, careers officers, nurses, doctors, counsellors as well as teachers. Very little back up from parents. They are the custom and we provide a service.
Contractibility - our email addresses are on the school website and parents just assume we can type a quick email whenever we want. No protection anymore of sending an email via the Head of Year of Head of Department.
Inclusion has reached crisis level and on average in a class of 30-32, I have at least 2 EHCPs and then another 8-10 with other problems. Very hard for one person to manage these different needs all of the time. TAs are so poorly paid and their time is stretched very thinly.
Constant changes in curriculum and the examination of my subject. In the time I've taught, I think I'm on the 4 or 5th exam spec.
Back in the day, I could teach the class. Seating plans were only ever needed for the real troublesome groups. Now a seating plan is vital and a bit like the trickiest game of chess because there's always that one kid who could cause issues on am empty room.
Coloured paper required for visual stress. Not sure when this became a thing but within one class I can easily have a students who needs the worksheet on green, one blue, one yellow, one pink, one with font Comic Sans, one on A3 and one with font 20. Ok, exaggeration but it's not far off.
General low level disruption. The level of rudeness, disrespect for teachers and school staff is amazing to see. Arguing back. It's draining. Setting detentions, rescheduling when they don't attend or when mummy says they don't deserve it as so and so didn't get a detention for doing the same thing.
I could go on but I'm depressing myself!