First, no need to thank me. I quit after 15 years in public education. Currently work for a company that provides exactly the types of specialized classrooms you are talking about to districts. Most districts just don’t have the capacity to meet the increased demand over the years. Waaaaay more kids need these services than even 10 years ago. See the other thread about kids that’s blowing up.
The number one reason teachers are leaving is exactly the scenario you outlined. They can’t teach. Number two is dealing with parents in relation to why they can’t teach. Throw in testing score pressure and needing a second job and we are getting a “hell no” from teachers.
FWIW, most districts want to do inclusion in a non-disruptive manner where the sped kids have assistants with them. This allows them to take breaks and only be in the class when they are focused and ready to learn. The reality ends up looking like the teacher being a 3 ring circus master all day then fielding parent complaints at the end of the day. The assistants get the shit kicked out of them for $15 an hour so even if the district is trying to hire, they usually can’t.
We can go back to self-contained classrooms for those kids, but then we have to pay for it. I recently wrote a proposal that was for fewer than 50 students and the cost was over 2 million a year. Now, we are taking on the toughest kids, many of which would be in a residential treatment facility without us. But most superintendents just aren’t going to write that check unless push comes to shove - ie the state getting involved.