One of the most egregious demands of the 9-5 is that your personal life should never touch your work life, to the point where you have to pretend to be positive and perform happiness in the name of professionalism. Being unhappy is ALWAYS considered unprofessional. Oh – someone near and dear to you just died? You can barely afford to live with this job and your pay isn't enough? Tough luck, be sure to come back with a smile! If you are a woman or POC this is worse, because if you aren't 10000% chipper all of the time, people will stick to your off days. If you actually have depression or mental health issues you are especially doomed.
I am pretty sure this expectation is also what prevents workers from actually unionizing. If you actually share what you authentically feel, we begin to realize more and more how much work deprives us of our humanity.