Another possible answer is that CHLs didn't volunteer for anything. A CHL is required in Texas to legally exercise a constitutional right to defend oneself; having one doesn't mean you volunteered, it means you paid the fee and took the course. Altho there are no doubt exceptions, the vast majority of non-LEO people who end up in gun battles generally didn't have the choice -- as did the NYC police officers -- about whether or how or why they were going to engage in a confrontation, and they generally do not have partners, back up, body armor, publicly funded-training-and-liability protection, or any of the other enhancements that a police officer has. So I would certainly cut a citizen more slack about missed shots than a police officer....
And an answer might be:
Because they were hired to do that job, you the CHL'er volunteered. The LEO is required under the terms of their employment to go out each day and purposely place them self in those difficult situations, making life and death decisions... You the CHL'er volunteered to do the same.
...
While it is true that one can be accurate with a heavy trigger, with practice, I think it speaks to the mindset of the NYPD and NYC in general to examine the actual purpose of the NY trigger. It is a mechanical substitute for trigger discipline - an attempt to avoid "accidental" discharges by people with sloppy trigger fingers. You may recall a couple years ago that the NYPD banned the use of Kahr pistols (which were very popular in the NYPD) as backup and off-duty guns, because Kahr could not or would not make the trigger heavy enough to please the NYPD decision makers.
The point above about the training range and the scant likelihood of any patrol officer receiving a decent amount of refresher (or even initial) training is probably dead-on. I know I have talked to police trainers from various departments who bemoan how far behind in re-quals their departments get; I'll bet if you could pull the data on that out of the NYPD you would find a large number of requalifications that are overdue, even if it is just a yearly requirement.
NYPD used to publish their "SOP 9" report, which was a yearly report on firearm discharges, and included how many boo-boos, how many confrontations, how many shots fired/shots hit opponent/shots missed etc. I think they have stopped publishing it to the public, but for a number of years the percentage of rounds that hit the guy they were shooting at pretty solidly hovered around 20%, quite often less. The report did not show, but I always suspected, that the hits were probably concentrated in a few well-trained individual police officers who hit their opponents several times, among a sea of others that did not (like the incident in the OP).
In any case, the incident in the OP reinforces my belief to immediately vacate the vicinity of any police activity I see going down. I love all the youtube videos that people put up showing public confrontations, I think they are a good learning tool, but I also think someone standing their videoing a potentially violent confrontation is taking on an unnecessary risk. But on the other hand perhaps they will serve as my cover as I boogie out of the area.