This affirms my belief that the secular increase in K-12 education costs is as much about the increasing share of children who are more expensive to educate (in terms of requiring free/subsdized meals, having various fees waived, needing more attention from specialists) as it is about more expensive input costs like healthcare and benefits for school employees.
Having been a substitute teacher and having seen about every aspect of education except for janitorial work, doing food service, or working in the school office... I can assure you that the free or subsidized meals pay for themselves in educational quality. It is far easier to teach kids who don't feel hunger pangs. Just about anything that gets better educational results has served me as a teacher -- even if 'only' a substitute. There's no techno-fix for hunger (also inadequate sleep, parents who show inadequate concern for their kids' learning, child abuse and neglect, or an anti-intellectual mass culture). There are manifestly good reasons for very rich parents sending their kids to expensive boarding schools whose dormitories are technologically advanced only to the age of electric lights.
Education has comparatively few administrators for the number of teachers. As a sub I have been basically an actor... and when you think about it, teaching is basically acting. I am not an effective social worker.