They also restrict themselves to jobs they can easily get to. Which in tech was basically impossible in, say, Boston 25 years ago.
A friend of mine made the observation that people mostly just don't do optional activities if they're hard or expensive to do. So if you live carless in a city with decent public transit, you mostly restrict your recreational activities and people you get together with to what's convenient and tend not to do things that require renting a car on a Friday night and returning it Sunday or Monday.