[LeifCarrotson]

I can also imagine of lots of future, intensely frustrating use cases where a user scans their card in a line at a point-of-sale, or is waiting on a "Confirming purchase, please wait" page on a website while your human in the loop puts this approval on hold for a few minutes until your cell phone finally rings.

Currently, human-in-the-loop approvals do happen, but they happen long after the purchase goes through - ever gotten a call from your bank's card services department as you were leaving a gas station on a road trip? Much more convenient for the common use case where the human approves the transaction than the rare cases when the bank is on the hook for the stolen gas.