Simple:
1. People lost ownership of the things they work on. In the early 1900s, more than half of the workforce was self-employed. Today, it is 10% in the US, 13% in the EU.
What you produce is not “yours”, it’s “your employer’s”. You don’t have ownership, and very limited to no agency.
2. People lost any tangible connection to the quality and quantity of their output.
Most workers don’t get rewarded for working harder and producing more or better output. On the contrary, they are often penalized with more and/or harder work.
To quote Office Space: “That makes a man work just hard enough not to get fired.”
3. People lost their humanity. They are no longer persons. They are resources. Human resources. And they are treated like it.
They are exploited for gain and dumped when no longer needed.