Enough that the country isn't constantly running massive deficits, and can afford to invest properly in infrastructure and other needed areas. Which we're clearly not doing right now.
We've been discussing, debating, and voting about taxes and wealth distribution for hundreds of years. If the solution were so simple, wouldn't you expect the problem to be solved by now?
So the OP says what society decides isn't fair, and you say that fairness is decided by society. It seems like there should be a less paradoxical way to reason about this.
Through debate, discussion, weighing up the pros and cons, and testing. We have tested our current set-up, and clearly it doesn't work for a large portion of society - now we alter it.