Rares are rising for anxiety, and diagnoses of ADHD & autism needing reasonable accommodations in the classroom, for sure. And yes, parents can help with this by ensuring very young children get enough time outdoors, moving, socialising with peers and doing creative activities.
But then parents are required to hand them over at the age of 4, where many primaries in this country are only geared up to process them en masse if they are compliant, quiet, middle-of-the-road kids. Starting each day with silence and stillness on the mat, followed by a round of phonics where it quickly becomes clear to all 30 in a class who is good at it & who isn't, is a surefire way to get any child outside of the middle wound up to a point they are nervous and scared about going in to school each day.
Parents repeat this story up and down the country. The science is very clear that once a child's nervous system is in sympathetic mode (adrenaline & cortisol up, fight/flight/freeze/fawn) rather than a chilled out parasympathetic state, their brains are so overwhelmed that they can't effectively take in new information or learn easily anyway.
Add to this the impact of a revolving door of teachers & TAs (my eldest was in Year 6 before he had the same teacher 5 days a week for a full school year, and he just about coped, but plenty of his peers got left behind because they were on permanent alert as they had no human connection with a 'key person' in the classroom for all of their formative years), and you've got a perfect environment to maximise the number of pupils who can't cope with a "normal" school day.
The over-academicisation of the UK primary curriculum is directly responsible for driving UP the number of children needing additional support. Reasonable adjustments like letting 6 year olds move more often than every 45 minutes and starting the day with movement and tactile tasks, not abstract phonics and maths shouldn't need a 2 year legal battle with a local authority. Other countries understand this is how 4-8 years olds SHOULD be learning. Every day!
Yes, there are some enlightened schools who manage it. But there are plenty who stoke the fires of anxiety and neurodevelopmental conditions far beyond what children could, in better circumstances, be capable of coping with.
Senior schools are now so enormous, and such a machine, that many pupils are having to eat at times of day that would prevent me - as an adult - from functioning anything approaching my best. Add in a lack of action on poor behaviour from their peers, agressive sound & lighting environments, stupid uniform rules/nowhere they can use within the time available between lessons to put a coat, so they are dripping wet from the walk in, fewer outlets for creative subjects & movement because of prioritising highly academic subjects and no.
I'm not surprised the number of children being opted out of mainstream schooling is on the rise.
Successive governments have chosen to cut budgets and prioritise lower tax rates ahead of giving the education science proves is effective to the next generation. Sure Start centres were decimated by the Conservatives, despite improving health, education & criminal justice outcomes & costing communities & councils far, far less over the long term.
We know what needs to be done to keep more young people in mainstream education. But no-one wants to pick up the bill for making it about more than cookie-cutter compliance.