I respect teachers deeply and think they are one of the most important persons outside of the home. What I have noticed the last 20 years is how much more we expect from the teachers. They do not only teach, they function as a communication channel between the school and the homes, they are psychologists every day and they are supposed to handle a lot that goes outside of teaching.
If this is acceptable or not is another question. Teachers do so many tasks that belong at home. Sex Ed for example is something parents should be involved in while many parents just let teachers deal with that. Manners... That is not the teacher's job, but in many cases it will be.
Kudos to the teachers out there. You do a fantastic job! Now, parents - time to do the parenting the teachers aren't paid to do!