Brushing aside the "giveaway" aspect of the parent comment, banks decide that money is gone (or inaccessible) because actors didn't respond within "reasonable timeframes" pretty frequently. For example:

- Banks are not legally obligated to honor checks older than 6 months

- Dormant accounts where the bank is unable to contact the account owner have their balances transferred to the state (State Seizure)

The latter probably makes a little more sense in this case since you could (depending on the issuer) just request another check from the source.