Right, this is what happens with eventually-consistent systems. In the case of a retail system most failures are easily resolved by either resulting in delayed

Right, this is what happens with eventually-consistent systems. In the case of a retail system most failures are easily resolved by either resulting in delayed delivery, drop-shipping, or refunding the customer's order. It's not the end of the world. Even banking works like this because settlements are done asynchronously. Some years ago there were several instances of an attack where someone got a hold of a rich middle easterner's debit card number and PIN, found a way to set the withdrawal limit up, then had crews of people hitting every ATM in Manhattan in one day. They were able to steal millions of dollars because the balance check was in real-time but the settlements weren't (so the balance was not drawn down).