I bet this guy is an asshole customer.

I've worked in retail (not GameStop, but other places) and every single store does this.

Customers come in all the time going "do you have any old merchandise you're going to throw away? I'll take it!" Or you find people digging through the trash hoping to find stuff and getting mad at employees when it's been damaged already.

Look, stuff doesn't wind up in the trash because stores hate poor people. Stuff winds up in the trash for lots of reasons.

First of all, things in the trash could be broken because... well, they're trash. Maybe a shipment of items showed up damaged, so they got tossed out. Maybe someone knocked stuff off the shelf and broke them, so they got tossed out. Maybe someone returned something defective, so it got tossed out.

Sometimes stuff in the trash is ruined for safety reasons. Pretty frequently there will be recalls on items that cannot be sold because they are not safe. These items are destroyed before they go in the trash so someone doesn't fish them out and hurt themselves. The last thing a store needs is a hobo who sets himself on fire because you decided to donate all the defective flashlights corporate told you to throw away.

Most of the time items that get thrown away are damaged to prevent fraud. Let's say OP here goes behind GameStop and takes a big box of games out of the dumpster. Then he goes back in to the same GameStop with his box and goes "hey, I want to trade these in/don't have a receipt and want to return these." Because OP's an asshole, he's willing to whine and complain and demand to speak to the manager's manager until he gets what he wants and now the store is out a shitload of money because they just bought their own garbage back.

Depending on the state, I think, stores actually get tax breaks for donating stuff, but for liability reasons, you can't just hand out stuff (also because if people knew you give away free old stuff, they'd never buy anything. You don't know how many customers hide stashes of merchandise in little nests around a store, wait for them to expire, and then come back and try to buy them at a discount or hope to get them for free). The stores I have worked at give any items that they need to get rid of that don't fall into the above categories to a registered charity, or a local Goodwill, or Salvation Army, or whatever. OP digging through the trash doesn't give the store an itemized list of donated merchandise that they can use when they file their taxes; actual charitable organizations do.

Of course, sometimes things just get thrown away because the manager is lazy and doesn't want to do the appropriate paperwork, but my guess is when big name video games are scratched up and thrown away, GameStop actually gets an order from EA or whoever telling them to destroy the merchandise.