It isn't always the same product, but you seem to want to ingore that point. Levis had to make a new line of clothing to supply pants cheap enough for Wal-Mart and Wal-Mart purchases enough units that manufacturers can run special models or batches just for Wal-Mart with different components. Sometimes, suppliers move their production overseas to make things cheaper. It's not the same. But don't believe me or the other people in this thread who actually like and shop at Wal-Mart who are also saying that quality is dropping. Do whatever you want. I think they are approaching the end of the line on sacrificing quality for cost.
But Levis considers that new line of clothes they made for Wal-Mart a life saver, they were a dieing company before then. And they had other things to get in line besides price before they could get to Wal-Mart (like reliable delivery, they were a pretty disorganized company and Wal-Mart doesn't like doing business with disorganized companies) which has also helped them improve their bottom line dramatically. Using Levis as an example of the nasty things Wal-Mart does to suppliers doesn't work, they saved Levis.