What you say is true of the colleges is also true of the union. And if I had paid tuition and dedicated a few years of my life to getting an education (which I did) I would most strenuously disagree with you about whether their job was essential or not. The particular issue the teachers seem to be most excised about is 'academic freedom'. I don't understand why an employee should have ANY freedom about how their job is done, let alone how they can insist upon it. You don't want to use the textbook the college wants you to use? Feel free to quit and go elsewhere.
Universities are not colleges. Academic freedom in university is very important when you have a government firing scientists for not doctoring their findings to match the “official” positions. It was also important when the American government was rounding up Marxists. More broadly, academics need the freedom to study controversial topics and come to critical conclusions without fear of losing their livelihood.
I don’t know what academic freedom means at the college level.