What? For this system to be truely trustless, the blockchain needs to be owned and maintained by all the people who use it. That means farmer, carrot juice guy, distributor, and retailer need to all have beefy computers with large hard drives to hold the entire blockchain and keep mining it.
Sure, it's great that you don't have to trust Amazon or Wal-Mart to trace the links back, but you could do just as well way more cheaply with a well-maintained independent 3rd-party with an AJAX API on top of a Postgres database. (Well, except for the part where said 3rd-party gets bought out by Twitter...)
>For this system to be truely trustless, the blockchain needs to be owned and maintained by all the people who use it. That means farmer, carrot juice guy, distributor, and retailer need to all have beefy computers with large hard drives to hold the entire blockchain and keep mining it.
Trustless isn't a well defined term so it is hard to disagree directly with what you are saying. However I would argue that most relying parties do not need to have the full state of the system to ensure they aren't cheated. In that they don't need information about other assets to track the assets they care about. For instance the carrot juice guy only needs to validate the chain of custody of the carrots. You could put a merkle proof for each custody change on a QR code on the side of the carrot box. The block headers are 70MB, the chain of custody is probably less than 10KB.
>Sure, it's great that you don't have to trust Amazon or Wal-Mart to trace the links back, but you could do just as well way more cheaply with a well-maintained independent 3rd-party with an AJAX API on top of a Postgres database.
I agree that a running PoW blockchain may be overkill for supply chain tracking. However a BFT distributed database maintained by several trustworthy institutions is probably better a Postgres database. Often blockchain is used as shorthand for "BFT distributed database maintained by several trustworthy institutions".
Sure, it's great that you don't have to trust Amazon or Wal-Mart to trace the links back, but you could do just as well way more cheaply with a well-maintained independent 3rd-party with an AJAX API on top of a Postgres database. (Well, except for the part where said 3rd-party gets bought out by Twitter...)