What just what? Why is it the school responsibility...
Because school and teachers reports are considered expert testimonial and therefore can be used in documenting need within the EHCP. This in turn can be used to apply for back up funding. parents testimonial is not. School are able to do things a parent can't.
Because how a child holds a pencil affects how a child learns and presents their Learning. How a child learns and presents their learning is the business of a school, how the child holds a pencil is the job of an OT. If an OT has failed to do their job a school cant do theirs.
Because schools are meant to care about kids.
Because schools might have to deal with less challenging behaviour if kids needs are met better in the first place.
It's not 9k and whilst what you are saying isnt exactly wrong isnt entirely correct either. here is a more complete representation
But if we are going to get political....
The "your taking money away from school through the EHCP" is a piss poor argument to try and persuade parents not to assert their childs rights under law.
Many of the more "minor" EHCP provisions can and should be implemented and funded on a whole school basis anyway as part of normal schooling (eg touch typing, sensory circuits, lexia) to children with or without an EHCP or SN as they produce whole scale benefits in both behaviour and academics.
There are things schools could do to keep SEN costs down and dont. one pe class should be given over to more SEN/physio style pilates. Again this would yield cost effective benefits.
All to often the child with a decent EHCP with one to one is used to fund a "class" TA. I have taken to telling the TAs in my class who they are meant to be supporting because all too often they don't know themselves,haven't bothered to check and have no idea what the need is.
It is actually most often the case that the child with an EHCP is used to prop up class funding whilst getting no benefit at all from the resource dedicated to them. And it's just plain wrong.
All to often you see a child in school epically sinking and a school that does nothing more than complain about problems the child has nothing in their power to resolve. Schools regulary fail to document and record need. It is left to parents to document, seek expensive independent professionals and ensure provision.
Those children whose parent can't, or won't are the ones who are left behind
If everyone was working together to document need, then there would be the evidence to back a political discussion around SEN funding. But its structural change that's necessary as much as funding. For example a camhs psychiatrist located in a school could diagnosis treat and build relationships ten times quicker than sat in isolated in a clinic (quicker better management might also ease mental health difficulties), recognising the value of earphones for kids with ADHD, seating kids in individual seats getting rid of restrictive uniforms.
Pointing the political finger and saying not us it's them is missing the point.