Eh, I don't think that's true, though. The most popular beers in the US at in the 4-5% range. Guinness is 4.2%, a lot of American "light" beers are between 3.8% and 4.4% ABV (Labatt Light is 4.0% for example).
Granted, in the US, outside of craft beers, you don't tend to see beers with the low...