I am not american, but both my parents were teachers, and they absolutely worked all year round, and longer than 8hr days. There are such a things as lesson plans, and marking homework, and being asked to do extra work such as editing the school paper, or coaching basketball, or whatever.

This idea that teachers work the same hours they are physically inside school and nothing else is laughable.

Though regardless, entry level software developers in the united states get six figures out of the gate, so it seems remarkably reasonable.