Hammurabi agrees with you (
https://avalon.law.yale.edu/ancient/hamframe.asp):
6. If any one steal the property of a temple or of the court, he shall be put to death, and also the one who receives the stolen thing from him shall be put to death.
9. If any one lose an article, and find it in the possession of another: if the person in whose possession the thing is found say "A merchant sold it to me, I paid for it before witnesses," and if the owner of the thing say, "I will bring witnesses who know my property," then shall the purchaser bring the merchant who sold it to him, and the witnesses before whom he bought it, and the owner shall bring witnesses who can identify his property. The judge shall examine their testimony--both of the witnesses before whom the price was paid, and of the witnesses who identify the lost article on oath. The merchant is then proved to be a thief and shall be put to death. The owner of the lost article receives his property, and he who bought it receives the money he paid from the estate of the merchant.
10. If the purchaser does not bring the merchant and the witnesses before whom he bought the article, but its owner bring witnesses who identify it, then the buyer is the thief and shall be put to death, and the owner receives the lost article.
But that's not how the law works in America. They have to prove the person had actual knowledge the property was stolen or should have known it was stolen. In this case it's easy because they had informants representing the property was stolen and the buyers still completed the sale. That's not always the case and can make these kinds of prosecutions harder. Cars are a little different because they are titled which makes disputes over ownership a lot more clear cut. And how was the refinery supposed to know to begin with? They never touched catalytic converters, they just got the metal powder from DG Auto. DG Auto was paid by wire transfer and from their perspective was probably not much different from any of their other scrap metal suppliers.