Director David Cromer has the ability to conjure expansive worlds from small, banal settings: For Meghan Kennedy’s The Counter, the set (designed with remarkable detail by Walt Spangler) occupies only a part of the space available on the stage of Roundabout’s Laura Pels Theatre. As he did with A Case for the Existence of God at Signature Theatre, Cromer encloses the characters in order to open them up. Of course, in order to perform this low-key magic, there must be sharply drawn, deeply human characters to work with.