Tax programs in Washington

I meant to post this earlier, but I never got around to it. But one thing I kept thinking to myself this tax season. Why on earth can you buy State Tax programs in Washington State. There is no state income tax, yet everywhere I go, I see the version of Turbo Tax State or Tax Cut State on the shelf.

Now, I could understand if it were just a few copies, but we are talking shelves and shelves. Sure, there are people like me, who work partially in another state for the year, who have to file state taxes somewhere else. But otherwise, for 99% of Washingtonians, there is no need to buy the state version of tax software.

Anyone have an explanation?