It&#x27;s transparency with the bank reserves.  With a bank, you actually don&#x27;t know if there is gold in their vault unless you go and verify if the gold is in the vault.  A consortium of banks can also multi-sign an address, so a certain amount of key holders will have to sign off to move the bitcoin, decreasing risk.  Then you can use the bank&#x27;s services to have the equivalent of credit cards, fast off chain transactions and so on.<p>I guess a similar gold vault problem is possible with private key control, but that is the same as verifying if the bank still has the keys to their gold vault, a much smaller problem.