This exactly. I'm a mandated reporter and I've felt compelled to report a few caregivers to child welfare over the years. Do A & P make me want to tear my hair out in frustration? Yes. But I wouldn't report them. A) nothing would happen apart from me getting laughed at, and b) as stated above, Abbie is fed, (relatively) clean, has access to doctors and therapists, and is (I believe) genuinely loved.
It would, of course, be better if she was in a public school for special needs (do they have those in the States?) where things could be monitored a little more closely. I do believe, as others have said before, that the Maasses get treated with kid gloves by JSA where as in the public system things like them always being late would not be tolerated (once and a while, sure - but not every day). A & P would also be held to task for maintaining/reinforcing behaviors and skills at home that were learned at school.