By the middle of the 20th Century teachers were being paid less and less for their work, and over time it became about having a few benefits that people claimed we had. 'Summers off' and pensions, I think were meant to offset the terrible pay. Some of my own teachers from high school talked to me about starting salaries from 1980 when they started, and I couldn't imagine that! By this point I think every teacher has accepted that they're not going to get rich off teaching.
So why do it? Well it's drawn people who genuinely care for the most part, and are pretty selfless at heart in most cases. If you don't get into the job for the money, then it must be because you care? How many times have we all said this line?
That's devolved into a lot of situations where we often judge each other about our motivations if we're not putting in more effort. You're clearly not a good teacher if you're not being a 'team player' on things. It's become very easy to guilt us all into sighing, and saying 'yes' about things we honestly shouldn't have to do.
Unfortunately there just aren't the legal protections for our profession - especially in Texas - that there should be. The 30 minute lunch is really one of the few 'sacred' items along with planning time that has managed to remain. It's become far too easy to guilt people out of defending themselves, and it just keeps devolving.