Photographs are things. Things have no tense. In the use of the English language, verbs have tense.
As the original poster explains, the CAPTIONS applied to photographs in media create the grammatical issue in their description of the photo's content. If the content is merely other 'things', there is no problem. "This is a red car." If the content of the photo includes action, newspapers and electronic media often describe the action in the present tense, even though the event obviously occurred in the past. "This is a plane crashing into the World Trade Center on September 11, 2001." "This is Hitler waving to troops in Berlin."
I do not know if languages other than English use the journalistic present tense in the captions of photos.