“All the teachers are really frustrated,” McDowell said. “We want to meet with parents. We send texts. We call. We try to have conversations. But at the same time, teachers know if they start doing it, it’ll just be expected of them.”
In this context, "It'll just be expected of them" means that teachers are worried that if they do more work than is required of them now, people will come to expect them to do that work in the future, and so they will never be able to stop doing that extra work.
Example: Teacher spends an additional hour meeting with a child's parents even when s/he is not required to be working. Then, later, if the child's parents want to meet with the teacher again, but s/he is not available, they will complain that the teacher is not doing his/her job, even though meeting with them was not required of the teacher to begin with.