Even so, the proportion of refunds paid because someone requested one, vs. the number of cards that were lost/destroyed in the laundry/fell through the cracks m

Even so, the proportion of refunds paid because someone requested one, vs. the number of cards that were lost/destroyed in the laundry/fell through the cracks means that they could keep some fractional amount on hand for those potential payments, and transfer the rest as "found money" to an operating account.