I don't like the conflation early in this thread between emotion-based school refusal, and truancy.
Yes, in the past they were conflated in some cases, but they are not entirely interchangeable. There is a big theoretical difference, and in fact that are pretty much the opposite of each other.
Truancy by definition is the act of avoiding or staying away from school Without a good reason. It is students who can, but don't want to go to school.
Emotion based school refusers are generally students who in theory do want to go to school, but can't. In a perfect world, most of them actually do want to be able to go to school like a "normal" kid, but due to a variety of emotional, mental health, social, neurological etc. reasons they can't manage it. If you asked most of them if they could click their fingers and change the situation so that they could attend school normally, they would say absolutely.
So you really shouldn't conflate the two. Yes in the past people did, which makes finding statistics about "school refusal" very hard, because historically it is conflated with truancy, and all manner of other absence in the statistical records. But they should never be treated as the same, and it should absolutely not be presumed that all of those who "truant" are refusers. A kid deciding to bunk off and miss a day of school because they don't want to go, is not the same as a child who wishes they could go but feels entirely unable to do so.
In a very short and over-simplified way:
Truancy =
Can go, but don't want to
Refusal =
Want to, but can't go