I don't see this.
Fairness is about mathematical expectation. Fairness means people have equal opportunity (often within a restricted domain, or ignoring certain starting conditions). There is [nearly?] always going to be a locus in which fairness is asserted outside which it is no longer the case.
* The race is fair because both runners run the same distance. Ah but the ground is uneven.
* The race is fair because the ground and distance is even. Ah but one runner is poor and hasn't eaten for days and so is weak.
* The race is fair as the runners have been nourished equally, the distance and going are controlled. Ah, but this runner's family have a genetic disposition that enables them to run faster without tiring ... et cetera.
If mankind didn't exist a situation could still be fair or unfair for a creature - a combat test for leadership is unfair because this creature had a greater opportunity for nourishment and so grew stronger than the others. That of course doesn't mean it's the wrong test, just that each creature able to take the test doesn't have equal opportunity to achieve through their own efforts.
>It's not fair to me that someone steals my car //
Everyone had opportunity to steal a car, including you, that's fair!
I don't equate fairness and just deserts [ie justice]. For example two people can compete in a fair competition but the least deserving - the one who made the least effort or the one whose lifestyle is least noble - can win; the competition was still fair though.
Because other peoples' concepts of fairness certainly do consider the ultra-rich.
While many might feel that kids of rich people have an unfair advantage, we haven't as a collective decided to do anything to put that to an end. We have made it a bit easier for non-rich kids to get some of the benefits that rich kids get like daily meals, access to education etc. but the gap is far too wide to bridge for everyone.
You can certainly try to design a social structure where nobody is rich or nobody gets preferential treatment but those haven't worked well so far for numerous other reasons. In a capitalistic, democratic/republic society, we haven't legislated the unfairness of being born rich, mostly because most of us don't think it is unfair enough to be illegal. In fact, most of us would think it is fair when looking at it from the parents' point of view. If you work hard and make a lot of money, why shouldn't your kids have it better than you did?
What I was trying to say to the parent was that fairness is not a concrete standard, especially when it comes to things many of us can disagree on.
So not entirely manmade.
Fairness is a fictional manmade concept. That we expect some sort of fairness in life is solely due to our social contract. It's not fair to me that someone steals my car and thus we have systems in place to address that. However, nothing in our laws, norms, ethics, or philosophy says that people must get everything they deserve and no more or no less. Hence the concept of fairness does not apply to kids of billionaires or friends of politically connected.