"Why they can't see investing into special education is cheaper in the long run (but it shouldn't be about the money) and just try to cut funding etc which ultimately ends up costing more and costing parents more too."
They do it (in part) because they are locked into taking a short term (5 year) view based around the electoral cycle.
I think this has got worse since the Referendum and as the Conservatives have become even more unstable. We have factions competing for attention and donors - not focusing on the country.
Now the Government's focus barely extends beyond the next news cycle.
Investing in the system would absolutely lead to better long term outcomes for those with SN and disabilities. It would also benefit those in MS schooling (pupils and staff) and future employers - and therefore HMRC.
But there needs to be the political vision for this to happen.