Oftentimes, we demand from our teacher what we wouldn't demand from any other type of worker or employee. They not only have to deal with the school board, but also with their own students (who don't make their lives any easier) and with those students' parents, who sometimes show up at the school demanding things from the teachers as if they were their own personal employees.
Teachers have a life outside of their work, and many of them have families to take care of and children of their own. They do their best with the material and the tools they have, and it's even silly on our part to demand things that are beyond what they can do.
In some weird situations, it's not us who demand too much from teachers; it's the district administration. In this case, some teachers at a school sometimes chose to clock out 10 minutes early once the kids had already left to avoid traffic and even pick up their own children from school, and no one seemed to have a problem with that. That was until someone up high took issue with it and installed a time clock to ensure that teachers were leaving not a minute before their contract hours. The teachers accepted it, but they also read the full contract and found out that all their extra hours that were not absolutely essential had to be paid extra. So they started having grading parties in the school bleachers after hours. They submitted so many requests for payment for extra hours that the administration finally had enough and left them in peace.
The great part is, they were abiding by their contract just fine until the admin started messing around. If all teachers needed to stay only the "necessary" hours, and the children were no longer there, it was not necessary for them to stay, so technically, they were already doing extra time without pay. Apparently, the lesson here is to never get into a conflict with teachers. They know their way around it.