Easier said than done, unfortunately. In suburbs, that'd require completely changing zoning, adding public transit, and waiting for new stores to be built in or near neighborhoods. In rural areas...I don't even think you can fix it, there's no infrastructure by design. (in cities, this usually isn't insurmountable, so there it'd just be incremental improvements)

The biggest roadblocks are the zoning and the public transit, because NIMBYs will come out of the woodwork to prevent any work being done. What it comes down to is that the people who can make laws affecting DUIs and the people who can lessen car dependency in an area aren't really the same people, so it's much more difficult to get done.