I've spent a few years in a couple of bulk commodities, and I'm sorry, but your thought about commodity markets is simply not true in my experience. There are e

I've spent a few years in a couple of bulk commodities, and I'm sorry, but your thought about commodity markets is simply not true in my experience. There are entire webs of institutions and mechanisms that make sure people do not defraud each other. Some keywords - look into Letters of Credit, Bills of Lading, Certificates of Origin, INCOTERMS, and the requirements to make these work (such as inspection certificates from independent third-party organisations like SGS or CIQ). Bulk commodities can be sampled, tested and certified as many as 4-8 times in between buyer and seller, on a dozen different criteria. Bulk commodity trading happens in an intrinsically low trust environment - it is frequently arms-length, cross-border, multiparty, for millions of dollars per transaction, and with a crazy number of different risks that have to be mitigated. The incentives to defect and come away millions richer are huge. And much of the system was developed for a time before the Internet. While this is a noble sentiment, the structure and transaction costs are absolutely essential for the whole thing to work.