Well, the US population is 300 million people and growing.
http://www.census.gov/population/www/popclockus.html
160 million Americans are those who have tried bikes and ditched them. Some of them can potentially return to biking if they find suitable bikes.

OK. You say that 100% of American women can drive stick shift cars.
Though, 90% of all cars sold in the USA are inferior automatic ones. If you don't trust me, go down a few blocks and count the percentage. So, they tried superior stick cars and ditched them.

What was the topic of this thread?
Are mountain bikes good for commuting? Sometimes, I say. And super cheap ones are the favorite among poor commuters.
Are commuter bikes good for commuting? Usually, I say.
Are folding bikes good for commuting? Yes, when combined with other means of transportation.
Are touring bikes good for commuting? Yes, for long commutes.
Are road bikes good for commuting? Rarely, too expensive if new. But used are good choice.