Best Buy, Circuit City, Blockbuster, Electronics Boutique, Comp USA, Gamestop, Babbages, Suncoast...and many, many other stores.
All stocked DVD very early on, and combined have a much bigger market than Wallmart.
Again, I'll iterate. For the vast majority of people, Wallmart and Target are not where they go to buy high end equipment. Wallmart and Target cater to, and it's very well documented that they do, low income customers. No matter what you do, no matter how you market, no matter how good your product is, Wallmart and Target's target market will not adopt until the final stages.
Nor is it a very large market, nor a very influential one. In fact, as far as adoption goes, the target market does not count. As above, it's the last one to adopt because it's the one with the very least expendable income.
People who shop at Wallmart but are not the market targetted will adopt regardless of Wallmart's stock practices. But because they also shop at other stores, and are discerning enough to make purchases at stores geared towards the product. Most of Wallmart's daily customers are not actually in the market that Wallmart caters to, for their own reasons.
Your entire arguement falls flat. By virtue of your arguement, Computers should not be widely available because almost no Wallmarts carry them. Nor should 5.1 surround sound systems. Or many other common items.
Wallmart and Target are not deciding factors for anything. If they were, we'd all be watching Full-Screen Pan and Scan movies.
Finally, the only reason why Wallmart has been such a success is because of the way they do buisness. This is coming to a close, with litigation pending against them or targetted at them in many states, Wallmart's methods of doing buisness will change soon and dramatically. Wallmart is the Microsoft of the retail world, and it's starting to catch up to them quickly.
Heck, Wallmart's been trying to put a store in my area for a year now. Each and every township in my area have systematically denied them access.
Can't be too great of a influence if they can't even influence themselves into a building permit in a major metropolitan area.