The FBI's Ballistic Protocols have driven the duty and defense ammo technology for the past 20+ years, but it has been painfully obvious during that time that a lot of folks were never aware of it. In fact, I've had Police Officers call me foolish for choosing a 9mm over a .40S&W.
Bullet technology, as a means to satisfy the FBI standards, ended the caliber wars many years ago, but apparently not too many people paid attention. Most modern duty/defensive loads, of all the service calipers, use bonded bullets with high quality powders that produce optimum velocities and little powder residue. The bullets penetrate from 12-16" in 10% ballistic gelatin, and expand reliably with maximum mass retention. All of this translating to excellent duty/defensive loads that are less offensive to the shooter while doing a heckuva job on target.
The 9mm Speer Gold Dots were achieving this is 2001, if not earlier, but the masses didn't stop to smell the roses, they just kept steamrolling over the Parabellum cartridge.
Why WOULDN'T more individuals, groups or agencies flock to the 9mm? Judging by the ammo availability during the past few panics, I think the majority is starting to get the message.
Now, all of this relates to the 9mm as a duty or defense cartridge with bi-pedal vermin as the primary concern. Obviously, there are better choices where potentially dangerous animals are concerned.