And "audit" not as in "spend millions on an auditing firm to do it for you", but audit as in "independently verify it yourself on your own computer".
Having a cryptographically verified history of everything my government is spending on would be cool, but due to the nature of the distributed ledger it would require private citizens be put under the same microscope. At least with the alternative of one central bank controlling one central database, there's some degree of restriction to personal information (I'd imagine the bank wouldn't let any average Joe request ledger data on their neighbor just for fun, but public interests would be fair game).
Simply knowing how many reserves the bank holds gives you no indication whatsoever of its solvency.
People are silent about it because Tether pumps their bags, sadly.