What if abandoning entire cartons of merchandise, and then shipping replacements, just has plain-old higher ROI for Amazon, than does peeling a driver off their route to get those parcels fed back into the system for re-routing?
I know Amazon already don't bother to process their own returns, instead selling those off in bulk lots for potentially far below the market value of the items (sort of like creditors selling off bad debts rather than trying to collect on them themselves.)
Both situations suggest a paradigm where human labor is by far the most expensive part of any logistics process, such that margin can always be increased simply by replacing workflows that involve even a little bit of human labor with fully-mechanized/externalized workflows, even when that brings service quality down.