In other words, the higher the marginal rate, the more lobbying for new loopholes goes on to prevent those high rates from actually being collected. And the more tax accountants and lawyers scour the endless depths of the tax code to figure out how to structure tax avoidance schemes that will be at least arguably legal.
And the rich have much more political influence than the not-so-rich. Do you think you could get your congressman or senator on the phone in ten minutes flat? I doubt I could. Do you think Warren Buffett could? See what I mean?