Years ago we were cleaning out our shop and had to scrap a lot of metal. At the scrap yard in Brooklyn there was a separate line for copper and aluminum vs iron and steel which was mostly a bulk dump job. Seemed like half of the line were homeless and destitute people. Many had shopping carts full of various pieces of aluminum and whatever, lots of AC condensers and copper tubing. There was a couple ahead of me, skinny, toothless, ragged and smelled of BO and urine were holding a few bundles of AV cables and an old extension cord in their hands - a scene of desperation.

The problem with policing scrap yards is you can't prove anyone stole anything. You could limit who can drop off scrap but then you create incentives for those people to purchase illicit scrap and pass it off as legit.