What other machines do you take apart and put back together and not test when you're finished? When you change your oil don't you start up the car and check for leaks, oil level, etc?
Another straw man.
I do a leak check because I have seen oil leaks...a few times in 40+ years. And in all honesty, because someone pinched an o-ring, or far more likely, failed to tighten the filter or the drain plug.
Human error.
I have never seen any of my handguns, rifles, what-have-you mysteriously stop working after a cleaning.
I made my living as a wrench-turner on airplanes for a lot of years (military and civilian) and oh, by the way, part of the maintenance instructions was to do a leak check. So I did it.
Those were the employer's rules, and were largely to protect against
human error. I understand that, as I saw guys who would forget to re-install a drain plug or fail to re-connect an oil line and burn up a 1/2 million dollar engine. Thanks to the union, all of them kept their jobs
Some of them burned up more than one engine. Some of them are probably still burning up engines.
For a number of years, I did my own work on all my motocross and later, road race motorcycles. In between races, major work was not unusual, including motor work. Wheel and brake swaps were a regular occurrence. No time for an ops check? No problem. Grid 'er up and go full blast into Turn One with forty other guys....many of whom are also doing their own maintenance between races too.
The consequences of failing to do any of that work correctly are not pleasant to consider...and yet, I am still here. Nearly 60 years old, I still ride every day of the year, and still do my own maintenance. Yep, I take a quick look under the bike after an oil change, more out of habit than anything else.
I am not saying that I am above making an error...if I were to leave a part out of my pistol during cleaning, then that would be a problem. I don't lose sleep over that hypothetical. I still work on my bikes, jump on them and go for a ride (although Turn One is a memory...)
BTW..."Trust but verify" is for the work of others.
Myself..it is just "trust".
Sound like misplaced self-confidence? Perhaps one day I will come to regret that.
If I cannot clean and re-assemble my 1911, S&W revolver or Kahr pistol without leaving out a part, i am an idiot, and deserve whatever ills befall me.
You can have my widow place it on my headstone...."He screwed up. I collected the insurance."