Isn't that just because people live in the suburbs? I think your example proves the opposite point to the one you're making - people would rather live in walkable mixed developments than have their destinations zoned away from their accommodation.
“Walkable” doesn’t give much room for options. 30 minutes walking covers far less area than 30 minutes driving.
Have you ever lived or travelled to a walkable city? You'd be surprised how much you can fit into a walkable area. In the UK basically all the cities are walkable just due to historical inertia; you can fit plenty of city into walkable areas. For bigger cities like London there's the underground system to travel further out.