In the days before the FDIC, if banks didn’t protect their assets they had no assets.
“They aim to welcome bandits with hot lead.”
https://www.mcall.com/la-me-fw-archives-1928-pistol-training-for-bank-tellers-20171120-story.html

Feb. 18, 1928: Los Angeles Police Chief James Davis, left, with First National Bank teller Madeline Morneau at the police shooting range in Elysian Park. (Los Angeles Times)
Thanks to Michael de Bethencourt of I’m With Roscoe for pointing out the article.