I agree with all of this.
But also @Sunnyduvet
I also think that some children exhibit quite early challenging behaviours and because of the way the world is now, instead of their parents looking after them and making sure they are around someone who understands them, making sure they get lots of outdoor play for example, they are put into before school and after school club and expected to behave. I think if a child is exhibiting early difficult behaviours then the best person to look after that child most (not all) of the time is the parents.
Life just doesn't work for parents and children nowadays. Lack of space, time, money, resources, mental bandwidth. Too many children being brought up by cash poor or time poor parents and living in inadequate accommodation. Too much fear and not enough love, affection and stability. Not because their parents don't love them, but because stress depletes our ability to actively demonstrate our love for our children in a way that nurtures and calms them.
Schools have a tough job but also they aren't set up to deal with the reality of life for many children nowadays. The curriculum is too narrow and there aren't enough staff or resources. There isn't enough space in many schools.
Especially in the early years, the focus should be on supervised, unstructured, outside play. Right up until ages 7 or 8. Completely screen free. The staff should help keep the children safe, resolve issues and help them build their social skills. Then, once they're calm and reception to learning, they should be called in (in small groups) for short, tailored bursts of learning. If they're unfocused or dysregulated, they should be sent back outside to play again until they're ready to focus. The emphasis should be on building self discipline, respect for others and relationships. But the reality is that this approach would be far too resource heavy for schools, and so they'll continue to fail to meet children's needs.
In the past, life was simpler, less frenetic and screen time was more limited. And teachers and parents often ruled with fear through shouting and physical punishments. So compliance was easier to secure... life was less complex for children and, if they weren't coping, fear of adults meant that they internalised this to a much greater extent. Hence a more orderly society.