I heard a saying from a real estate salesperson, "Pay from a JOB keeps you Just Over Broke." I understand that there is valid reason for the term "wage slave." One way the average employee is a slave is that you as an adult have to ask permission from another adult (who may differ from you only in title or seniority if that) simply to go and relieve yourself in the restroom or you may be assigned a time to eat or take a break.
You may be forced to wear certain things that are not comfortable or are embarrassing. Also, you can be required to ask permission simply to stretch your legs, plan a doctor's visit, a family trip, or a vacation...if you can afford it. You may be made to feel badly simply by asking for a raise you deserve or may even be treated rudely because of this.
It's possible to see the "masters" at the top getting bigger bonuses & perks each year while the mid to lower level employees get no raises for years & are told to do more with less & less. You may have others attempting to undermine you and get you tossed out of the job simply because you choose to not stroke their egos or be a part of something that is not up to your moral standards. There are many examples but these are just a few. The words used to describe this are up to each individual but I know enough to know that there are similarities. Unfortunately many prefer to lie to themselves in an effort to deny reality.