And many people who buy from Amazon know Amazon must happen to sell some goods that are stolen, yet they still shop there. If everyone had to cease buying/selling because they know their counterparty must have some stolen goods then trade would literally ground to a halt.

I don't know if it's a crime if it's just "somewhere we must be buying stolen goods, but we don't know where." I'm not a lawyer but I think knowing that the specific item you bought/sold was stolen would look differently in court than just having some vague knowledge there must be stolen stuff somewhere in the supply chain.