By "avoid" I mean avoid the intention of having a progressive tax system, not like legal tax avoidance. I know we wrote in plenty of legal loopholes to classify income such that rich people can pay less.

But it's not even the case that rich people pay capital gains necessarily. It's very easy to live off debt and never realize gains. When you die, your basis resets and you never pay any taxes ever.

This is how people like Bezos and Trump have years where they don't pay any taxes at all.