"To compare incomes across countries, the researchers applied a common adjustment known as purchasing power parity".
Source: http://www.nytimes.com/2014/04/23/upshot/about-the-data.html
Also, "Bubba" might have more cars but that's because his two teenage daughters need a car each to get to school since there is no subway, no busses and no sidewalks. Bubba's land might be 50,000 sq feet 40 miles from DC , but many people might prefer Francois' 5,000 sq feet plot in the outskirts of Paris. American cities are more sprawling, European usually compact - so it's really difficult to compare even simple things like land.
Bubba's McMansion is large, indeed, but it's built with a light frame construction with outer walls of plywood or composite and asphalt shingles as a roof. These American carton box houses just don't convince European home buyers. Francois lives in a brick house with clay tiles on the roof.
Bubba has little or no insulation against winter cold or summer heat. So his eight ACs are running on electricity all year around to heat up or cool down the home. Francois generally only turns up his radiators 5 months of the year and the district heating is very efficient. He only has AC in the three rooms facing South and there is rarely a need to turn them on. What is better?