It didn’t, having been to kinder myself sending 3 kids through. Occasional accidents, yes, but no conscientious parent sends their 4-5 year old to school in diapers because they were never potty trained.
I never knew of 5 year old’s having accidents.
When we were 4 we went to nursery school and like Kindergarten that was half a day. I don’t know what these public schools are pulling now but I liked the old way better.
Looks to me their new way is failing.