Tax rates are determined by something like trial and error now, but the test is not whether they produce equality, but simply how much you can extract from each

Tax rates are determined by something like trial and error now, but the test is not whether they produce equality, but simply how much you can extract from each group without causing social disasters. You can take away about half the money rich people make before you start to break your economy, but if you took half the money poor people made, they wouldn't have enough left to live. Hence you get progressive taxation.