Virtually all of the rights we learn about in grade school are suspended in the workplace. And while employees do have the ability to quit, they a.) still have to find some other dictator to work for and b.) are much more heavily impacted by a loss of income than the employer is the individual loss of skill.
So the dictators we work for day in and day out are aligned with other dictators. You aren't entitled to free speech in your office, so why would you expect to the people running your office to care about your free speech after hours?
edit: I'm still surprised that people are incapable of question the ideology that shapes your worldview. The very concept that "well you're working for someone else so the of course suspension of liberties is okay" is doctrine that you have been lead to believe since birth precisely because it benefits those people in power.