Because it is not a law of nature. Fairness is a human invention, the universe and physics even biology operates on principles of randomness, cause -and - effect and so survival is on justice, morality or equal outcomes. A philosopher named Yuval Noah Harari once said that " the concepts like justice, right and fairness only exist in human imagination.". The society we leave in is shaped by people and human natures are driven by individuals to protect their own status and secure advantages. Biologically, one is born into abject poverty or inherits wealth, none of these is a law of nature is a matter of randomness.
If fairness is a product of our imagination, then a meat grinder and a serial killer are on equal status. If we’re going to view everything from such a materialistic perspective...
If fairness is a product of our imagination, then the concepts of good and evil are also products of our imagination. What about beauty and ugliness? What about mathematical expressions? Equations? How have these values become a common form of expression throughout the entire history of humanity, and how have mathematical equations come to occupy a position above them, one that is not even bound by time?
By reducing concepts such as fairness, beauty and ugliness, or good and evil to nature, Harari presents a reductive materialism or a scientific naturalist identity. In the ancient world, people chose instead to place everything within the concept of fairness.