How is the U.S. tax system different?

Clive Crook reports:

A new report by the Organization for Economic Cooperation and Development shows that in the middle of the last decade — i.e., after the Bush tax cuts were introduced — the U.S. income tax was about as strongly redistributive as income taxes in Canada, Denmark, Finland, the Netherlands and Sweden. You might have noticed that the CBO report on top incomes was widely quoted, but one finding got less attention: Between 1979 and 2007, “the federal individual income tax became slightly more progressive.”  [TC: note that this last sentence can mean a number of different things/]

The awkward truth is that the U.S. income tax system is anomalous not because it taxes the rich lightly but because it taxes everybody else lightly.