I am working on some posts on income inequality, especially as compared between nations. One thing I have been thinking about is whether the US GINI (a measure of income inequality) is overstated because the US has a tiered retail system that gives lower income people access to lower prices (though for sometimes lower quality goods). We have Wal-Mart and Family Dollar, discount retail concepts that are rare, and often illegal (due to limitations on retail discounting) in European countries.
On a sort of purchasing power parity basis, I wonder if this has any impact in narrowing the US effective GINI. Of course, this mitigating factor is somewhat mitigated itself by the fact that a number of urban areas with some of the poorest families (e.g. Washington DC) restrict entry of these low-cost retail establishments.