I was only a substitute for a short amount of time at a high school. I am a college professor now and let's just say those worlds are wildly different.
Grade school teachers are expected to get there at 7:30am or earlier and lose their whole entire day. Sometimes they are required to stay an extra hour for pick up, but they don't get paid for that. I just can't imagine working in that setting AND being so underappreciated. I was MISERABLE as a substitute, and these people do it everyday for years. They don't just go to work and go home, they also make class plans and email people outside of work hours. Sometimes they have conference period where they can communicate during that hour but sometimes they don't even have that.