This one contrived example does favor Perl, and will beat Haskell by a small margin. But as soon as the user says "Oh, sorry, I was mistaken, I needed the number and the next letter" or something like that, Haskell is on top again. As Haskell is one of the greatest languages for handling "Oh, sorry, actually..." requisites, and Perl one of the worst.
As long as the "actually..." only needs a small change to a simple regex (as in your example), perl probably wins the "actually..." game as well until you pull in enough libraries that the Haskell looks a lot like the perl. It's when the regex starts getting overcomplicated and the Haskell breaks out parser combinators that Haskell probably moves into the lead.
As you say, though, the margin perl maintains is small.
I just thought the express claim being made significantly oversold it. Whichever approach you take with the Haskell in the example under discussion, modifying the Haskell is not easier than adding a handful of characters to a simple regex.