Because you are no longer expected to just teach your specific field of study; you are expected to be a therapist, babysitter, parole officer, and social worker.
You can expect disrespectful behavior daily. In some districts, you can expect violence daily. Parents are either not engaged or constantly looking for offense.
I saw the writing on the wall 30 years ago and moved into the private sector. I found other ways to teach outside of the public school setting.
Until parents start taking power back, insisting that their kids act civilized, and demanding that schools only teach and not endoctrinate, nothing will change.
Nothing will change until government education is fully exposed as the child abuse that it is, and that fact is finally accepted by the population. True change will come when the government school system is shut down. There are NO good government schools.