Wrong. As of a coincidental trip there yesterday, Apple TV in stock and for sale in Sam's Clubs (North Texas) for $289.
Remember in addition to DVDs, Wal-Mart sells iPods and stocks a full price range of iTunes Gift/Store-Credit Cards. So Wal-Mart can sell content for your DVD player, or via iTunes Cards, content for your Apple TV. How much money they make on one or the other, I have no idea, but certainly the Sam's Club arm of the company is just selling another device for which you can buy content at the non-membership, more everyday Super Wal-Mart stores.
Sam's Club has for some time sold more upscale items -- HDTVs, Xbox 360s then PS3s and Wiis, good quality furniture, etc. Now they carry even more. Wal-Mart has always pandered to the working-stiff demographic, with expurgated music CDS -- and even some DVDs, I think -- a very abbreviated magazine rack and an inventory of discounted book titles selected for content so as not to enrage or even lose their American Bible-belt customers. About the only thing they didn't refuse to sell due to content were video games. Not so anymore. At least not so, depending on your demographic area. (And remember, my demographic area is urban and semi-urban North Texas, a traditionally very conservative region; and our Wal-Mart stores have completely changed.)
They came under some public scrutiny for their overseas labor policies, for their domestic labor policies and wages, and for healthcare programs for their employees. So with limited selection, favoring knock-off brands, some of perfectly good quality but not the known brands, over name brands, I think they realized due to some shift in public sentiment and the inconvenience of finding upscale brand products in their stores, they realized they were pretty rapidly bleeding market share to more expensive Target Stores; Target being not as cost-conscious but with a broader inventory of items that the upper middle class will spend a lot for along with their groceries. They're completely remodeling many Super Wal-Marts, carrying outright literature as well as Tom Clancy novels, carrying unexpurgated CDs, carrying any new DVD movie Target will carry, carrying Blu-ray and HD DVD movies -- a better selection of both than Target, and the best Blu-ray inventory I've seen in any retail chain store of any kind -- and carrying popular name brands like Apple iPods.
Anyway, that's by way of explanation. You're wrong, but a couple years ago you would have been quite right. The Wal-Mart umbrella, including the public retail stores and membership-based, wholesale Sam's Clubs, would not have sold products that would have moved sales away from the Wal-Mart retail brand. But I think people were saying, basically, well if I can't get an Apple TV at Sam's I'll get one at Apple and I'll buy my movies and music straight from iTunes, and I'll be a little miffed at Sam's Club for being so insular and maybe I won't buy my soft drinks and big bags of frozen chicken there quite so often, either, and I'll look elsewhere for that HDTV for the bedroom.
Target is however still winning in selection and price on new and rather obscure bands and their CDs, and overall book selection; as well, their in-house furniture and home decor lines are better designed and of higher quality.