Taxes are just one problem to consider.
Labor costs are a big issue when you compare the EU countries and the US. Asia owns a lot of the labor markets.
The EU has a more varied labor rate -- you can't compare French and Bulgarian labor rates. The US has a smaller variation but still the locale matters a lot:
France vs. Bulgaria -- Bulgarian per household income is only 43% of French per household income
California vs. Mississippi -- in Mississippi per household income is only 64% of the per household income in California.
A lot depends on the locale and if the market is local, in that ecomomic zone (domestic) or global.
I think these locales are comparible and near weighted.
Code:
$36,907.00 FR
$15,941.00 BG
43% Differential
$57,287.00 CA
$36,919.00 MS
64% Differential
Sources:
EU: World Bank
US: US Census