Is professional life naturally a series of unfairness?

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I ran my own business for about 7 years and am now in my 6th month at a small to medium-sized enterprise. Strangely, here, if you do your job well, your workload just keeps increasing, while people who perform worse than me or cause more trouble are moved to easier tasks. I felt so disillusioned that I once asked my team leader about it.
I asked if I could be moved to a different role, even just temporarily, but they dodged the question, saying there were no openings (T/O) or something like that..
As it turns out, there actually were openings, but they just wouldn't move me. Instead, they prioritize task assignments for people they like (since the team leader is female, she only assigns easy tasks to male employees). Even when it's obvious that others are struggling, they continue to provide unfair benefits. Is a company naturally like this?;; I am quite taken aback.
This isn't a one-time occurrence; they keep assigning easy tasks primarily to male employees and low-performers, while the difficult tasks are continuously piled onto the same people..