Well beyond the exploitation of folks on the spectrum dressed up as job training paying them pennies on the dollar because the law allows it as someone said above, it has ridiculous business practices in terms of sales. I used to enjoy shopping for cheap items that were usually posted on eBay until goodwill created their own website. Completely unregulated and no recourse. You pay for shipping and handling everything. They have secret employees to shillbid to drive up the price on items that are being "watched" because I seen the same items from the same locations go up for sale again days after the auction "ended" and I was "outbid" because I wasn't willing to pay a ridiculous price for a used item. Another confirmation of this was I once received an item that accidentally contained a document that had teirs with a point system on it for how much they wanted to get for the item versus how much it started out when the auction begins. Have also been sent useless items, for example a pair of boots where the sole was completely broken. Was told I had to send it back with my own money. They price out people from buying anything good or name brand which was the whole point of secondhand shops, killing thrifting and the treasure hunt. They dump all the crap stuff at the stores and sort through the expensive items and try to upsell them online. They get diamond rings for free and sell them for thousands of dollars on their website and guarantee nothing. I once saw, shit you not, them try to sell an imperial Faberge egg. They of course could not confirm if it was real since only so many of them were made. But they kept trying to repost it and repost it and repost it after each time it would sell for thousands. I even saw them try to sell Finnish Army decorations that were swastikas from their small stint fighting the russians. All of the higher-ups at Goodwill makes six figures while they take free items, up charge them, and pay folks less than slavery wages. Do not ever donate your stuff to them.
the rabbit hole goes even further. Most of the crap clothing doesn't even hang around in America to "help the less fortunate" or whatever. Goodwill exports it to countries in East Africa, where tons of used clothes are basically just
thrown on the docks and sold to resellers by the pound.
While some of these resellers and Goodwill make plenty of money and East Africans occasionally get to wear some fancy western brand on the cheap, this practice has also destroyed the local textile industry so extensively that some governments (Uganda and Rwanda) in the region have outright banned the import of used clothing. Oh yeah, and when those countries banned the practice, the US government punished them by expelling them from the African Growth and Opportunity Act and cancelling other trade preferences.
In short: Fuck Goodwill, they're an instrument of American imperialism
I forgot to mention I worked in a building that shared a warehouse with Goodwill and you're right. Anything that doesn't sell they just compressed into these giant cubes so they can put on shipping containers and make more money.