In August 2019, I never would have imagined that a banking regulator would be require customers to wear masks.  In today's changed world, banking regulators are doing just that.  The California Department of Business Oversight in its August monthly bulletin describes how it is monitoring face-mask compliance at the financial institutions that it regulates:

"The DBO mobilized drive-by spot checks of various branch and storefront locations to verify compliance with the Governor’s order throughout the state. These checks determined whether notices were posted on public facing doors, observed customers entering and exiting the premises, and noted whether a greeter or monitor was at the location restricting access or providing personal protective equipment (PPE)."

I guess Willie Sutton would have to enter a bank without a mask to show that he is there to rob the place and not simply make a deposit. 

I do have one small cavil with the DBO's description, the Governor did not issue an executive order requiring face masks.  The order referenced by the DBO was this guidance issued by the California Department of Public Health.