What's in a "the"?

The runner-up for this week's New York Times Wedding Announcement of the Week was the union between Tara Smith and Thomas Struth. If it wasn't for the made-for-the-movies romance between Amy Knapp and Myron Walden I would have gone with Smith/Struth because of a rather curious wording in the very first sentence of their announcement.

Tara Bray Smith, a writer, and Thomas Struth, the photographer, were married yesterday...

Why is she a writer while he is the photographer? What the wording suggests is that Struth is a recognizable figure, one that would lead a reader to wonder, "Is that the Thomas Struth? THE photographer? The New York Times answers, "Indeed, it is Thomas Struth, the photographer."

However, it's arguable that Ms. Smith is herself an instantly recognizable name. After all, her memoir, West of Then: A Mother, a Daughter, and a Journey Past Paradise, was published by a major publisher. It's not every one that gets published by a big time publisher. Doesn't that warrant a "the" instead of a "a" in front of "writer"?

If it's merely a question of who is more famous, then Struth seems to warrant the "the." Two days after the wedding announcement, the Times has a major article on Struth's new exhibit in today's paper. Still, it seems unfair and rather priggish to dub one partner "a writer" while the other is "the photographer." As a matter of recognizability, I would argue that neither is sufficiently famous to warrant being called "the photographer." I doubt a casual reader of the Times knows who Struth is.

Is there a rule that covers this? At what point does one become "the" instead of "a"?