Except the failure mode for Amazon shipping software (in this example) is equally or more likely to be the item is never shipped or a completely different item

Except the failure mode for Amazon shipping software (in this example) is equally or more likely to be the item is never shipped or a completely different item is shipped, rather than the correct item being delayed. The latter two are more difficult to deal with. Also, even in the delay case, more people are depending on Amazon for items they truly need, like groceries. Delays can matter.