[dragonwriter]

> The US has the most progressive taxation system among all developed nations.

That's extremely misleading; the US does functions other developed countries do via social welfare programs via the tax system (deductions and credits such as the EITC, tuition and student loan interest deductions, etc.)

Doing a like-for-like comparison—either removing the welfare system pieces out of the US tax system in the comparison or, even moreso, doing an all-in comparison of tax + transfer payments, would tell a very different story.