It's not that it's not allowed but it's not required. Labor market is very unequal in information on one hand, where it's much harder for individuals to know what is their value for the business and how are they doing versus the peers. Then there is strong arming through credit obligations and work + commute time that effectively makes it very prohibitive for people to object.
And so since you can exploit the people, most businesses will. That's a very easy way to improve your business results.
People are able to tighten up the belt if they believe in the cause. And you can even rewind the clock on the capitalist system to see that people were contributing more and taking less for themselves.
Erosion of social structure was helped a LOT by targeted propaganda. Some of which is influencing your own thought process.
Think about it.