I owned 6 P320's in my training business and ran many, many novices and experienced shooters through my courses with nary an issue or malfunction. It is one of the easiest platforms to use to teach novices to shoot accurately, due to the ergonomics.
SOMETHING needs to pull that trigger to make it fire. I think if you drop it enough times you can probably break it and make it fire, but then that is true of other guns as well.
I have the perspective of having been a LE instructor since 1971. I was training a lot of people when Glock first arrived on the scene and everybody was transitioning from revolvers. As Glock made their way into LE, we started learning of injuries from negligent discharges, some tragic. We had a name for it: "Glock Leg". Why? Fingers on triggers by cops who had been brought up on 12 pound revolver triggers. We also saw occasional ND's with S&W gen 3 guns for the same reason. As a point of interest, I can also tell you tgat in 1971 many LEO's of the day believed 1911's were unsafe for duty carry.
I investigated a few ND's where reportedly "it just went off" but came down to operator negligence.
Holster manufacturers of security holsters recommend drawing the unloaded pistol in training a minimum of 200 times before going live, to build neuromuscular memory. I was surprised to see agencies handing out new duty holsters with no training whatsoever. I watched and video recorded many students and was surprised at the number of even experienced shooters who were putting fingers on triggers as the gun was coming out of the holster. They had no idea they were doing it.
I believe there have been rare uncommanded discharges due to holster issues or malfunction. Guns are after all a mechanical devices and all things mechanical can fail.
But it is fingers or something contacting triggers that are the culprits in virtually all of these injuries. Glock and Glock fans hate SIG because SIG out-Glocked them with the 320 and 365, and got the DoD contract. The p320 controversy is largely fanned by the Glock mafia and media sensation. I personally prefer a 1911 type handgun for carry but would have no problem carrying a P320 for duty or EDC.