A lot of kids these days are damaged beyond repair before they even set foot in a classroom. Probably the best the teaches can hope for is instilling some vague sense that there are some rules in the world...
Boy, do I have anecdotes to prove your statement. (I have a lot of teacher relatives and friends).
An older retired teacher friend of mine was bored and decided to do some substituting in a city school. They gave her a kindergarten class. At recess, a little boy was running after a little girl, wagging his exposed tiny willy at her, and yelling "Git down, 'ho!"
I am not making this up.