Like I said before, everyday all around you, there are off duty officers conceal carrying. They were never trained to conceal carry. Do you or anyone else notice it?
I notice. I have often seen either off-duty LE, or on-duty "plain clothes" LE carrying. You are right, they aren't necessarily trained to "not print" and most make little effort to do anything other than the most basic concealment. They don't have to....a quick flash of tin (Badge) will get them out of any trouble a mere citizen would find themselves in under similar circumstances.
As for LE being better trained and therefore less likely to make a "mistake" in a shooting....maybe, but I think it's more the individual rather than the general training. Let's look at the New York shooting where NYPD fired at a guy who had just shot someone else. What was the number of innocent bystanders that got hit? What about the recent incidents in LA where not once, but twice, police opened up on two innocent citizens, who's vehicles didn't match the suspect and where none of the victims remotely resembled the guy they were looking for? Were any of those shootings a demonstration of the police's superior training and decision making capabilities? What about the NYPD transit officer that pulled out his firearm instead of his TASER and shot the guy in the subway?
The police, as the above cases demonstrate, are not subject to the same rules and laws as "us" in regards to use of force/firearms. Do you really think that you would have been found innocent of "reckless disregard" or "reckless endangerment" had you, as a CCW, shot 9 innocents trying to shoot someone else? Or that you'd be home in your bed if you had shot the heck out of a vehicle that was not an immediate threat, and in doing so, shot an innocent woman? Or that the media would have let those incidents slip so quietly into the past if they involved a CCW rather than the police?
Don't get me wrong, I understand the police have a difficult job, and that life changing decisions are sometimes made in a split second. I don't begrudge them that or support most of what happens when officers are forced into those difficult situations. But, rather I mention it to dispel that all too common notion that the police are so much better trained than "us" and that is why "we" should be held to different, and higher standards should we undertake carrying a firearm (where allowed to legally do so).