This photograph is much different from much of Evans work in that it is close-in and includes no "live subjects".
On the surface it would seem to vary from his more well-known images that record the misery of the Great Depression.
And yet, it is very much within the "spirit" of his WPA assignment which was to document life in rural America in the 1930's.
With this particular photo I think he is trying to show that the "town photographer" was an integral part of village/rural life in the 1930's. People, almost no matter how strained their finances were, felt it was important to be photographed at certain "key" life milestones.
Not too long ago the NY Times had an article (probably seen by many here) about the "discovery" of a small town photographer's photos (I think he worked in Arkansas) and how their very "ordinariness" was so important in depicting the emphasis folks placed on recording their important life events (oops - run on sentence - sorry).
Here (I think), Evans has actually captured the display window of such a small town photographer. In those days, cameras were not readily available to most folks - and going "into to town" to the "photographer" to record an important life event was a family outing. And many small towns had a photo shop that was probably busy as hell every Saturday morning!