Browski and I work in NYC where for the reasons he stated unions are necessary.
I've watched principals dismantle departments to get rid of high salaries teachers. I've seen a 15 year physics teacher cut because the principal felt the students don't need physics and she hired a young earth science teacher instead. The same thing takes place with music, art, dance and languages. Some superintendents and principals only care about numbers graduating not scholarship. In the corporate world this wouldn't happen ( and in an affluent suburb too).
I worked for a principal and cut a gym space into small classrooms; a few of us protested and my friend with little seniority was cut. She couldn't get rid of me but she had her lackeys observe me everyday for a month, the observations were unofficial nevertheless this wasn't pleasant for me or the students.
Politically, Browski and I have disagreed but we both understand the need for a strong union.
Education is a process not a product you can't take the bottom line approach a boss in the corporate world will take.