The thing that kills walkability in the USA are the hyper scale stores and malls where everyone wants a mega store that has everything - one stop shops. They are too big to fit in small neighborhoods so they have to be built in a commercial district or large strip mall. And since they are big and house many shoppers at once they need big parking lots. Then they need big streets to feed those big parking lots. These big ass stores DEMAND cars and are very much a part of the problem.
If you want more walkability then incentivize lots of small shops over single giant shops. I would also argue that neighborhoods that are all residential for blocks and blocks are another problem so zoning should force a minimal commercial allotment to ensure walkable neighborhoods.