"The Power of the Principal."
A principal can make a teacher’s life miserable:
By giving them the cold shoulder;
By spreading negative words about them to staff and parents;
By not supporting them in situations with parents;
By not supporting their discipline
Principals can load up classes with the most difficult and lowest performing students.
Principals can change the teacher’s assignment even though in LAUSD assignments are supposed to be selected by seniority. The on site union representative is most unlikely to stand up for a teacher fearing the above negative treatment. Calling the union is totally fruitless as the union leaders are most concerned about spending the dues and maintaining their perks, privileges, and pensions just like the LAUSD downtown bureaucracy that they totally mirror.
This has been going on forever.
The Kingdom of LAUSD—a top down pyramid (empire) with the serfs—teachers--at the absolute bottom of the pyramid.