Some 80 million Americans fit in the marketing demographic of individuals between the ages of 16 and 34. Researchers have found they drive less, with a larger than historically normal percentage not possessing a license. In fact 26 % in 2010 do not have a license, an astonishing figure.
And yes, smartphones assist those young people in getting better train and bus connections.
But in fact, sampling where these folks live certainly will skew results and interpretation. Beyond the coasts and large cities, Americans are path dependent on the car -- and thus in Dayton Ohio, every one of my current students has a car. In New York, Philadelphia, LA, Chicago, the percentages would be far less. But remember, America is a big country and the center of it in many important respects is not on the coasts, but in the Heartland. And market researchers need to remember that when releasing information that can be sensationalized for the influential coastal newspapers and media.