The headline U.S. corporate tax is higher than that of many other countries, but it also has many more loopholes than the corporate tax of many other countries. As a result, the effective corporate tax rate in the U.S. is relatively low, around 13%: http://en.wikipedia.org/wiki/File:Effective_Corporate_Tax_Ra...
However I believe the parent's point was just that taxes on personal earned income represent a much larger share of total U.S. tax receipts than taxes on corporate income do, i.e. the U.S. mainly taxes labor income. And that is true; the corporate income tax accounts for only 10% of federal tax receipts: http://www.cbpp.org/cms/?fa=view&id=3822
However I believe the parent's point was just that taxes on personal earned income represent a much larger share of total U.S. tax receipts than taxes on corporate income do, i.e. the U.S. mainly taxes labor income. And that is true; the corporate income tax accounts for only 10% of federal tax receipts: http://www.cbpp.org/cms/?fa=view&id=3822