I'm not sure how this is relevant. But, on the off chance it is, I'll summarise the Swedish situation: no, they absolutely do not leave it to families. They are broadly in favour of inclusion and integration but are constantly reviewing the evidence as to how this approach affects different children. It is illegal to keep a register of disabilities in Sweden and therefore less categorisation of children. In Italy, inclusion is preferred but individual needs are considered. Again, in Italy pedagogy is more important than clinical diagnosis and this is reflected in teacher training. The recess good work regarding SEND and teacher training in the UK up to about 2012 but the obsession with breaking teachers as quickly as possible and allowing MATs to train their own teachers according to their own ethos has, in my opinion, severely limited this.
According to the data, the UK has 5 times the rate of SEN than is average in the EU - make of that what you will in terms of who diagnosis actually serves in the UK. 5 times.
I'm still not sure of the relevance to the current topic, children with genuine SEND are more likely to be affected negatively by a 'no toilet' policy.
A strange but perhaps apt analogy might be in what has happened in football stadium toilets over the last decade. They used to be almost literal cess pits, were heavily policed and were foci for violence and vandalism. A trend of making them attractive, clean and properly equipped began with the building of new stadiums; they are no longer policed and fans seem to have responded well to being trusted and treated like humans. There is almost no violence and vandalism is practically unheard of.
My personal experience of European schools is that students are trusted more in all aspects of school life and respond positively. When I was part of SLT in a school, some of us advocated trying this approach - it wasn't perfect, but the vast majority of pupils appreciated not being forced to suffer because of a minority of offenders. We had a period of time when SLT focussed heavily on behaviour in communal spaces and we sanctioned, excluded and, in some instances, prosecuted those who didn't buy into our sense of community. I know this was reversed since me and some other leaders moved on and behaviour in general has deteriorated significantly.