The article jumps from talking about teenagers to talking about people under 40. I think different factors are at play. Among teens, their basic needs are ofte

The article jumps from talking about teenagers to talking about people under 40. I think different factors are at play. Among teens, their basic needs are often already met by their family, teens are less likely to work than a generation ago, and a lot of their interaction is online anyway. Teen physical independence dropped for other reasons and the appeal of cars went with it. For adults I think you're right about only high income people being able to live in neighborhoods with close amenities, but also reliance on delivery services, Uber/Lyft are also ways that high income lifestyle can make you dependent on cars while not owning one yourself.