See eg. https://www.oecd.org/els/soc/growingunequalincomedistributionandpovertyinoecdcountries.htm https://www.oecd.org/els/soc/growingunequalincomedistributio.

See eg. https://www.oecd.org/els/soc/growingunequalincomedistributionandpovertyinoecdcountries.htm https://www.oecd.org/els/soc/growingunequalincomedistributio... which states that the United States has the most progressive tax system among developed countries. It has not fundamentally changed since 2008.