It's a complex set of difficulties for teachers. I remember when the National Curriculum came in, each teacher in our school was presented with a large three-drawer filing cabinet. I wondered why. I soon found out. Ten huge and massively heavy grey ring-folders (National Curriculum 'subjects') were brought in by a staggering Welfare Assistant. Followed by about seven other, smaller folders for Lesson Plans, Assessment of Lessons Completed, Stock Orders, Special Needs Assessments, on and on and on. I was drowning in A4 sheets of paper. Those three drawers were soon full to bursting.

Then The Timetable. ('Literacy Hour', and many other cages in which to lock and stultify children's brains). Learning now comprised ten mutually exclusive subjects, which appeared to be the GCSE course divided into indigestible chunks thought suitable for children from 8yrs old. (hence The Depression and The Abdication)

Not long afterwards the Inspectors arrived, mostly a bunch of fools who couldn't teach and hadn't a clue what they were supposed to do. The things they said to me and the 'suggestions' they made were so annoying I was hard put not to knock them senseless and flee the building.
If today's teachers have these sorts of things to endure, it's no wonder they look elsewhere, for better salaries, happier workplaces, far less stress and more appreciation. Good luck to them.