I actually see parents destroying the relationship between teachers and students. In my generation all of the adults were on the same side of the table.
The parents, teachers, and school administration were united in the efforts to make sure the student was doing what was needed to succeed. If acted up in school the parent took the teacher's side.
In the U.S. there are many parents who have no ideal what there children are up to and don't even know when report cards will be issued. In other instances if a teacher dares to punish their child for unruly behavior a parent will likely threaten or look for ways to press charges against the teacher and the school administrators.
The children sense the teachers are powerless. Therefore the students respect level for teachers has dropped tremendously. Students who don't pass or score high enough on tests are now a reflection of (the teacher's ability). Never mind the child may not have been doing the work necessary to retain the knowledge given or English might be a second language for student.
No politician can get elected by placing any blame on the parents (AKA) their voting constituents! Therefore it's the teachers and the school who are at fault for all students poor perfomance.