Not to be that guy, but:
What is the unique selling point to choose blockchain over other solutions already existing in the market such as Tibco, or even a centralized database containing the various business rules and logic? After all, there already is implicit trust in the system described, and no decentralization.
Or perhaps I haven't understood correctly.
I am speculating here...but maybe they made every carrier and vendor a client and node of the blockchain network. From which they can add their own transactions as they happen and the entire chain will carry an accurate representation of the transactions from every carrier. Making it easy to collate in almost real-time.
> After all, there already is implicit trust in the system described, and no decentralization. Or perhaps I haven't understood correctly.
I also don't have all the answers, but thinking more about it, maybe it is the case, that even though there is implicit trust, the third-party freight carriers might not want to depend on a centralised system wholly managed by Walmart? This could be due to opaqueness of such a system.