US vs. EU Airports & Heliports

(http://www.cia.gov/cia/publications/factbook/index.html),

the US had an estimated 14,807 airports (5,128 with paved runways of which 188 over 3,047 m/10,000 ft.) and 155 heliports in 2003, whereas the European Union (EU) only had 3,130 airports (and only 1,834 with paved runways) and 94 heliports. Yet in July 2004 the EU had an estimated population of 456.3 millionliving over 4.0 million sq. km compared to only 293.0 million living over 9.6 million sq. km in the US. Discussthe reasons behind these discrepancies