There is a historical-sociological reason why, despite USA being considered the "fortress of capitalism" (which in principle allows for an arbitrary degree of wealth and income inequality),still, rich people are taxed less in Europe (which supposedly takes a more, ahem, "socialist" approach), even if we exclude indirect taxes:
In Europe with its historical burden, prior to the industrial revolution the aristocracy had its wealth in land, since we are talking about agricultural economies. The central authorities of the day (the King) taxed the aristocrats which in turn, in order to cover both the King's taxes and their own living, taxed the peasants with exorbitant "tax rates", in the form of almost total appropriation of agricultural produce, given the socio-economic laws of the era. So for centuries land per se was not essentially taxed (after all it was "god-given"): it was labor that was taxed almost to death.
Add to this the fact that these social arrangements were embedded in a theocratic system that gave them religious credence, count again the length of time that it lasted, and we can perhaps understand why modern Property taxes in Europe tend to be lower than Property taxes in USA, were the apparently more individualistic culture cuts both ways -meaning that the State has also and "individualistic" approach to things: if it is after a certain amount of revenues, it has fewer qualms to take them where it can find them. In Europe the same concern, constrained by tradition not to be wholly fulfilled through Property taxes, and ideologically and socially pressed to exhibit a redistributional character in income taxation, has led to larger indirect taxes, like VAT.
So either including or not indirect taxes, the tendency goes in the same direction: relative tax burden is heavier for "Europe's poorer", than "USA's poorer". Of course this does not conclude on whether it is better to "be poor in USA or in Europe", since one should also quantify the social benefits that the poorer receive in Europe compared to the USA, as regards, education, health, direct subsidies, etc.