I'm not sure why you are blaming teachers' unions for the ongoing difficulties. Working conditions, not salaries, are the #1 priority for teachers and their unions. An out-of-control child is often a hazard to other children and a drain on the mental health of a teacher who has dozens of other children who also have needs.

Yes, acting out can be a symptom of other issues but your suggestion seems to be that misbehaviour is fostered by in-class deficiencies. Sometimes that is true and there is much that schools can do in most cases. But there are some children who are so angry, so impulsive, so disruptive, so far behind academically, etc that it is unreasonable to expect him/her to function effectively in a regular class.

I agree with your point about finding the right program. For most kids, the right program is a regular program. Unfortunately, many effective programs & facilities have closed during the past few decades. Some of these programs involved other Ministries.