Two people walking down a narrow alley with large buildings on each side.
Two people are walking down an alley on their way home from work.
Just because they are walking in a narrow alley in the city does not mean they are on the way home. Just because they are walking in a city does not mean they work there.
Not all people walking down are for home from work.
People walking does not always imply they are on their way home from work.