twins,
You are comparing apples and oranges.
Apples: Military, police, and security companies are PAID to perform a function, part of which requires the carriage and potential use of firearms. To varying extents, their employers are liable for the actions of (and harms done by) those personnel. Liability, both in terms of financial judgments and in potential loss of the public trust, is a major factor encouraging the setting of some standard of training.
Oranges: Private citizens, interested in defending themselves against potential abuses by bad guys, or potential attack by animals (for a moment the other day, I thought I might have to draw on an Akita, running loose, that came at me while I was riding my bike; happily, I was able to avoid that by jumping off the bike, using the bike as a barrier between me and the dog, and talking to him until he retreated - I like dogs and have no desire to harm one, but I am also not about to fight with an Akita.)
Now, if you can't establish that training among the private citizenry actually reduces accident rates, then you are arguing that they should train as do military, police, and security forces for what reason? You do realize that mandatory training has the following potentials for abuse, I hope:
1) Anti-RKBA governments could make training prohibitive, either by making it very expensive; scheduling it rarely; scheduling it at inconvenient times; scheduling it for prohibitive amounts of time (such as M-F, 8-5);
2) Even where governments would not pull such stunts, some people who might be able to afford a defensive firearm and a minimal supply of ammo may not have the disposable cash to put toward the training course; those same people might work multiple jobs and have no time to put toward the training course; they may also have limited transportation and no ability to physically get to where the course would be administered.
Now, we've had similar discussions on TFL before. You should know that I love training. I've trained with Mas Ayoob, as well as on multiple occasions with Uncle Sam. I shoot IDPA; I have a firing range in my west pasture; I have also trained for decades in martial arts. I am all for training, but I am not all for mandatory training.
I think, if you do a search, you will find similar sentiments expressed by Pax, Frank Ettin, Mas, Marty Hayes, Rob Pincus...
They all recommend training as much as is feasible, but last I checked not one of them favors mandatory training requirements for private ownership.