I once worked as a substitute in the school district that once sued the State of New York over the constitutionality of property-based returns of state aid to education (the more money the district's homeowners property is worth the more money the schools get, even if they don't arguable need it to babysit those with futures). They lost it's constitutional have the inequality, the state ruled. So they started the lottery system.
There seems to be an inequality in the substitute system too. The lesson plans are assumed to be just picked up and taught for the day at very low wages in comparison to what is the largest union in the US of A, its teachers. They should either raise the substitutes wages above the substitute janitors (which I also worked at) or decide the syllabus can wait a day and let the kids read.