You're right that car centric transportation is entrenched, but this is the wrong statistic to prove that point. The US is a huge country and the overall density of roads (km/100km2) is lower than Europe.
https://en.wikipedia.org/wiki/List_of_countries_by_road_netw...
man is measure of all things. its density of people is lower too.
Europe isn't a country though - difficult to do a comparison as a about 40% of Europe is the European part of Russia which has a much lower road density than the US, mind you European Russia is going to be the part that has the highest road density of that country.