I thought this article would be relevant given the current political climate. This covers a historical event in which the police were out-gunned and the aftermath playing an important role in the gear-augmentation of police forces.

WSJ article https://web.archive.org/web/20150702091610/http://www.police...

See also https://en.wikipedia.org/wiki/1986_FBI_Miami_shootout , which "contributed to the increasing trend of law enforcement agencies to switch from revolvers to semi-automatics across the nation".

Or further back in time. "Another reason for the creation of SWAT teams was the fear of lone or barricaded gunmen who might outperform police in a shootout, as happened in Austin with Charles Whitman." - https://en.wikipedia.org/wiki/SWAT

It's a series of step functions, ratcheting up the police to handle new worst-case scenarios. And training them to think that anything can be a new worst-case scenarios. Like selling lose cigarettes or potentially using a fake $20.