Found out about this a few months ago. As a collector, this just absolutely irritates me. Also they throw out DS game cases all the time. That's why you see so many DS games in sleeves or in a big bowl, or in the counter.
I will never buy a game without the case and manual. Disc-only/cartridge-only=No buy no matter how cheap it is
I can only tolerate cartridge-only on say like N64 games and GBA games where getting it with packaging is already tough enough (It pays to keep packaging, the resale value goes up), especially as those came in cardboard boxes.
Oh BTW, one of the guys they mentioned had found a PS3 before.
What I don't get is that once you throw away something it is suppossedly belongs to the public. Look at when people pull stuff out of celeberities garbage and sell it. What's the difference? Cool thing to do would be to grab the stuff from the dumpster and turn around and resell it to them if possible!