I've spoken with long-time staff at my local co-op. They have (historically) taken the finest parts away from the general public bins and either display them in cases (for sale at higher prices) or take them for private use. One of the perks of working so many hours there.
They sell parts for one to take home, though. I have donated 100x more than I have purchased there, simply because I don't want the burden of carrying a large parts inventory in my home.