Goodwill doesn't just smash them, they sort out the saleable or fixable ones for the store. They take the rest apart and salvage power supplies, hard disks, heat sinks, motherboards, video cards, etc. for resale in the third world. Dead parts are binned, plastic is separated from steel and aluminum for recycling, and so on. It's not like everything that comes in gets shredded immediately. Really old stuff and especially unusual stuff gets looked at by the museum director, then may go on sale in the "oldies" section of the store, or may go to the museum collection.
But if they have put some 68K Macs out in the store for $25 or $40 and nobody buys them, they get scrapped. At this point, the Macs that are coming into Goodwill are mostly G4s and a few seriously dead G5s. The stream of G3 iMacs is down to a trickle. Apples kind of stand out in the mountain of H-P, Dell, and Gateway PCs.
