Replying nastiness with kindness is a really difficult thing to do, especially if your boss was really unfair to you. It gives you a bad taste being nice to someone who doesn't deserve to be treated nicely, but who you have to treat nicely because they are your superior (and they can screw you if you so much as lift a finger against them)

Why is this kind of thing happening? Why are employees 'forced' to treat their superiors with respect even when they don't deserve it? Why can employees not voice out their opinion, their version of things without the fear of repercussion? Isn't this oppression? I thought this kind of thing shouldn't happen in civilised society.

Isn't there a mechanism to defend employees from getting bullied at work by their superiors? I don't think anyone should be afraid to go to work, I don't think anyone should be subjected to fear by their superiors. This isn't how a civilised society should be.