A pet peeve

Am I the only person who finds it incredibly irritating when there is a long, long line to discover that the person in front of me, who must have known for quite a while that she was going to pay by check, takes out her check book and starts filling in the information only after the total has been rung up?

I seldom pay by check, but when I do, if I’ve been standing in line, I use that time to fill in the date, payee and, sometimes, my signature.  That way, once I know the total, I can swiftly fill in the amount and be done with it.  Why do these people always act as if it’s a surprise that they need to fill in that information?