Earlier quoted context omitted.
We can use less cars and use more trains. Energy efficiency is also an addition in the crease of available energy source, since said energy sources can be deployed to more productive, less harmful processes. Walking is also good, and it would probably do us good to personally increase humans' basal metabolism.
trains are exclusively fixed point-to-point. many cities are not constructed for walking and/or are 110 in the summer. respectfully, screw walking.
Changing society is hard isn't an excuse to continue the status quo, nor some edge case you envisioned is an excuse to not encourage walking, cycling, or public transit whenever possible.