In my state, charters don't have to use a lottery, and they're free to reject out-of-district applicants. It's easy to reject an IEP/SST or disabled student and cover your motive.
There are plenty of out-of-district applicants because they are exempt from needing their home district's approval to leave -- you don't even have to notify your home district. Whereas, if you want to leave to enroll at a different traditional school, your home district can say no.
Accordingly, charters are filled with affluent families and traditional schools have become a gravity well for IEP/SST students, students with severe psychological problems, emotional problems, physical disabilities, etc.
Our state average per-school for IEP/SST students is 9 percent. My local traditional school is at 22 percent.
There are district-paid personal attendants who accompany some students for no other reason than to protect other students, staff and property from being harmed, and mostly document incidents rather than curtail them.
The classic example is when a student decides to get up and walk out of class on his own, shouting down the hallway at nobody and nothing in particular and then climbs playground equipment to shout some more.
It's become routine for staff to lock office and classroom doors when a student goes 'walkabout' to prevent damage to school property. You know, otherwise the student walks into the office, sits down at a workstation and then gets violent when he's not allowed to play computer games.
The alternative to this situation is paying a lot more to provide full in-home instruction on a per-student basis, which the state doesn't come close to covering, but we now do for some students.
The district got in trouble when it had three students suspended at the same time, triggering a state investigation. The pressure is to not suspend, and never expel, students no matter what they do. Just document incidents.
And when you talk to students, you count 10 positive things you say to the student before saying 1 'negative' thing like, "Did you do your homework yesterday?" And you document those 10-to-1 comments to prove you followed procedure.
I stopped by another local elementary school. There was a student sitting under the overhang of the secretary's desk in her own world while an attendant sat nearby documenting. It's far safer to let the situation play out as long as nothing and nobody is being physically harmed.