Does it really need to be interpreted?

Here's an interesting piece that ran in the New York Times about the value of a good annotation. The author starts with Hardy and moves on to Austen and touches on a few other authors.

I don't normally like annotations, unless Terry Pratchett is making them, because I usually feel the notes are interrupting the story flow to tell me something I already know. But the author of this piece makes me want to buy at least one of the books he mentions, the Austen annotation that is so thorough.

But he loses me at the end of the article when he says:

Readers who complete “The Annotated Pride and Prejudice” have a leg up when tackling “So You Think You Know Jane Austen?” This challenging quiz book, intended for professional-grade Austen readers only, arranges questions, in four ascending levels of difficulty for each novel. Some questions are short, factual and to the point, like “How old is Darcy?” (The answer is 28.) Others require interpretation. Why, for instance, does Wickham elope with Lydia, since he is a mercenary cad and she has no fortune? The authors, John Sutherland and Deirdre Le Faye, need more than a page to answer this one.

I thought it was pretty obvious why Wickham elopes with Lydia. He doesn't. She may think they're going to get married but Wickham is out to ruin her, whether because he is a pleasure loving rake who's a bit of a sociopath, not caring how many damaged girls he leaves in his path, or because he wants to try and hurt Darcy indirectly or a combination of the two is debatable. Either way he has no plans for marriage and the only thing that changes his mind is the huge sum of money Darcy gives him to do the right thing. At the moment they run away together it doesn't matter that Lydia hasn't a feather to fly with because Wickham isn't out for money. It's sex, pure and simple.