I agree it's a worth exploring. Just spitballing, part of it may be the cost of maintaining old buildings, particularly when changing demographics lead to over-capacity in some neighborhoods and under-capacity in others. It may also stem from financial mismanagement. There is generally less parental engagement, since poor families have more pressing concerns, so it's easier for waste or fraud to go unchecked. I don't know, none of these explanations are particularly convincing.