Brings to mind the movie "It's a Wonderful Life" with Jimmy Stewart. His uncle Billy mishandles a large sum of money running the bank, and depositors demand their savings be withdrawn. Stewart explains to customers that their money is tied up in their neighbors' loans for remodeling, businesses etc., and could they accept only a portion of their accounts. Banks just don't have a lot of money laying around in their vault.
That has as much to do with being robbed as it does with reserves.
We (The bank where I worked) had a Branch in our town get robbed for more than $100k one Friday afternoon. Shortly thereafter, they cut back on the amount of cash in any branch. You could still get your big cash withdrawals…but you would have to go to the main branch or wait a day to have it delivered.
99.9% of people understand that.
Some people think they should have $20 million in each branch vault. That is not going to happen.
It’s funny…in the BIG vault, I have seen stacks of cash that more than cover every request for cash for a few weeks.