I want to chime in that currently in Michigan, substitute teachers can make up to $100-$200 per day through EduStaff (temp agency), however they do not get to unionize, no insurance or sick days, or benefits, plus they can can reassigned last minute. My partner had $100 worth of labor stolen from their last paycheck too, and a labyrinthine process to complain about it. The requirements are a bachelor's degree (though many from other fields with Masters degrees work as subs).
We've gotten into it with 'professional' certified teachers about who's more "valueable" (them or subs), but, I think it's divisive thinking. Both types of educators need to be on the same team and boost eachother up.