To the people saying terry toweling and poor access to soap and water are the reasons we're seeing an increase, maybe, but it isn't just that.
It was only the 1970s when children with disabilities were allowed to access an education, this was strengthened in 2001 with the SEN code of practice and reinforced by the EQ2010.
A lot of children before this time that weren't toilet trained just wouldn't be in school.
More and more specialist provisions are being closed down or being increasingly harder to access, waiting lists for diagnosis are getting longer, so there is obviously an increase in these children being present in mainstream from 4 years old, but without diagnoses.
Back in the day, you just wouldn't hear about them.
I've told the story before a few times across different threads about how my neighbour, the one who currently lives opposite me, had a daughter hardly anyone knew about who had obvious SEN. When my mum was a child and lived in this very house, she would call on the boy who lived there, and it was only when she was older around 10 that she learnt there was another child who was just hidden from the world because having a child with disabilities back then was seen as shameful, and their poorly understood behaviours would be slammed as poor parenting and it would be community gossip.
She was not an isolated case either.
So it isn't that potty training in schools was less of a big deal because these disabilities weren't around, it was just that these people weren't in school.
Even earlier in history these people would just be institutionalised.
We're just unfortunately in a place where we're pushing for acceptance but there are not the resources to facilitate these children who absolutely should be allowed to be integrated into society and receive an education, coupled with cut and underfunded services from the past 14 years of austerity.
If you'd like you can also add in the trauma and isolation of the pandemic, which many professionals disagree with, but then many progressional do agree with, which affects whole family units and their ability to operate, and as mentioned extraordinary lengthy waiting lists for diagnosis and support.