High School Teacher here.
1. A common statement heard from teens is: "You have to EARN my respect". Someone, somewhere, has taught them that respect for elders or authority is not a given. I did not raise my children that way.
2. Too many parents want to be their children's friend. It is much easier to say "yes" than "no". Hence, no boundaries are set and respect for others must be "earned".
3. School discipline policies rarely address the lack of respect. A student calls a teacher "a dumb ass bitch" he or she "may" serve a detention at most. At the student's convenience, of course. I'd prefer a written apology. One full page; double spaced; one inch margin, with proper use of transitional phrases. Now that's punishment.
When I was in High School I have seen teachers get cussed out many times, I recall one time the kid called the teacher an asshole, and one kid told our creative writing teacher fuck you, not much really happened. They were taken to the office on both occasions, the kid in my creative writing class got switched to a different class but nothing happened the kid who called the teacher an asshole, neither of them was suspended.
Good thing they weren't Nuns ......
Maybe the teachers were assholes?
It DOES Happen, ya know.