As mentions several times in the thread - it is not a "Walmart" thing or policy - it is the manuafacturer/publisher. I'd bet Target does something similar with their magazines (although they don't carry very many).
I don't know about magazines, but I recently had to furnish my new two bedroom apt. so I ended up buying a bunch of cheap assemble yourself furniture from Target and as I was assembling the drop-leaf dining room table I saw that one of the leaves had a big noticeable scratch so I returned to the store to see if they could exchange out just that piece for me since the rest was put together. They were very nice and fished out the piece for me, but when I went to try to fit my original piece back into the other package they told me not to bother, that they would just be throwing it away now. I felt so guilty! But they explained the whole manufacturer policy of crediting them for damaged goods and how they weren't allowed to reduce the price. I mean, this was a set including chairs that was completely functional except for a scratch. The customer service guy went on and on about all the good stuff they throw away-- he was particularly pained by the 42" flat screen that was thrown away because of a small scratch the week before, lol.
My younger brother works at Michaels art store and he tells me about all the high qality artgoods with just damaged packaging that go into the trash compactor... hopefully he'll work out a system to save some of that doomed art gear for me, but no luck yet. I know my grocery store throws out about 3-4 heaping grocery carts of bakery goods every night (c'mon! throw a chocolate cake this way! no one's lookin!) ostensibly because of lawsuits, according to one bakery lady.
The culture of waste is so systematic and institutionalized at a time when we need the opposite from big companies, etc. Well, I'll stop the rant here since this has nothing to do with sewing! ::sorry::
BTW, I will be checking those dumpsters! Hopefully there are no compactors and the patterns aren't full of bleach.