It isn't fair because entropy is uncaring. You can't control all the variables and so even if you had perfectly balanced society in spreadsheets, you couldn't implement it. This is the fallacy of city planners too, you can't control the human factor, the weather, the global community etc.
Even if we just talk money in one community, you could give everyone the exact same amount of money and through no fault of their own, some people would lose it and some would benefit wildly, because of the human factor. Person A starts a coffee shop that goes bust, person B starts a coffee shop that does well, just due to timing or luck or even the weather the month they opened.
How do you suggest we make life fair? Some things you can make changes to equalize, but how are you going to equalize height or intelligence or something like that?
Even if we just talk money in one community, you could give everyone the exact same amount of money and through no fault of their own, some people would lose it and some would benefit wildly, because of the human factor. Person A starts a coffee shop that goes bust, person B starts a coffee shop that does well, just due to timing or luck or even the weather the month they opened.