It's difficult, because a network of suppliers and processors can go very deep and involve a great number of branches: a batch (or "lot") of red peppers from a

It's difficult, because a network of suppliers and processors can go very deep and involve a great number of branches: a batch (or "lot") of red peppers from a farm could be split up and shipped, via various shippers, to a variety of manufacturers for quite different purposes. Getting everyone coordinated to use a central database is... difficult. Instead big market movers (think Walmart, Kroger, et al.) can say: "look, if you want to do business with us, then you and all your suppliers and their processors and suppliers in turn, and so on, need to transact lot and batch numbers and related info into this distributed ledger thingy, which we will all be a part of running [think industry-specific Hyperledger (or similar) application, not the Bitcoin or Ethereum blockhains per se]. The data transacted has to conform to certain ISO standards. If the data's not there, all the way back to origin, we'll stop doing business with you. You have 5 years to get ready. Get started."