Wow, reading you recalls lots of ideas inside my spirit!!
First, the cake example is brilliant in its simplicity. By reducing the abstract concept of "fairness" to something as tangible as slicing a cake between parent and child, you expose how subjective fairness truly is.
There’s no universal formula because every value system introduces a different denominator: body size, metabolism, effort, experience, need, or even power. What feels fair to one person becomes injustice in another’s eyes—not because of facts, but because of perspective.
This mirrors real-life conflicts, especially in emotionally charged situations like divorce or community dynamics (like on Hive). The brilliance lies in showing that fairness isn’t broken—we just pretend it’s objective when it’s inherently interpretive.
You don’t just argue this—you make us feel it, taste it, almost see the uneven slices on the plate.

Second, your reflection unintentionally echoes Dale Carnegie’s wisdom: "Criticism is futile because it puts a person on the defensive and makes them strive to justify themselves." He goes further, saying that criticism stems from pride and ignorance of the other’s inner world—and ultimately achieves nothing but division.
Your friend’s destructive post-divorce campaign is a perfect example of unconscious criticism turned into action. It wasn't about justice or fairness; it was ego masked as moral righteousness. And what’s tragic is how common this is.
We judge others for not walking away gracefully, for being bitter, for lashing out—but rarely do we pause to ask: What pain are they carrying that I cannot see? What experiences shaped their response? Without that empathy, our judgment becomes its own form of violence.

So yes—there is no fairness in humanity.
But perhaps there’s something better: understanding... And maybe, just maybe, if we stopped measuring fairness so fiercely, we’d have more energy to practice tolerance, compassion, and self-awareness—the only currencies that actually transform lives.