If you wanted to sit down and toss around the potential things that can happen with a car, truck or motorcycle that can result in it no longer working right ... while you're traveling at speed ... it can be sobering.
Fortunately, these sorts of things don't happen with well-made vehicles, properly maintained, often enough to make me lose that much sleep.
Ditto firearms.
Sure, anything mechanical can experience an unexpected failure of a part or an assembly, and sometimes at the most inopportune moment.
I don't stay awake at night thinking about it, though. I inspect my firearms used in the role of defensive weapons carefully and maintain them (including preventive maintenance) according to standards and recommendations promoted by manufacturers. (In my case this also means according to what I've learned while being an armorer, as well.)
The plunger tube issue can occur, although during all the years I've owned, used and maintained various 1911-style pistols I've only personally seen it occur twice, that I can recall.
Just based on my personal experience as a firearms owner & user, as well as a LE firearms instructor and armorer, I'd expect the significant amount of functioning issues which occur, day in & day out, to be caused by the shooter in some manner, followed by potential ammunition issues to a much lesser degree. Sometimes it can be the firearm, though.
Sometimes frequent examination and inspection can help catch some potential issues when they're still developing but haven't reached the point where they might cause functioning problems. For example, I've caught some weakening extractor springs and chipped extractors during inspections before they actually caused functioning issues on some service weapons. That's one of the reasons manufacturers who provide armorer training often recommend some reasonably periodic, such as annual, inspections of dedicated defensive service weapons.
Since you mention the 1911 design, though ...
Recently, I stopped by the range at my former agency and was doing some shooting and visiting. One of the younger guys came over with a major name brand 1911 pistol which was exhibiting some functioning problems when he was qualifying. When I looked at the gun I noticed the safety lock (thumb safety) had shifted outward a bit from the frame ... just enough for the plunger spring/plunger assembly to have fallen out of the plunger tube. The tube appeared firmly attached to the frame, but the safety itself would apparently shift from out of the proper position under recoil. Considering the make/model of the 1911 in question, and that it was an off-duty weapon and not an issued weapon, I suggested he contact the manufacturer and request a warranty repair. I made at least one other suggestion for something he might want to bring to the manufacturer's attention when he contacted them, as well.
Sometimes things happen ...
I own 5 1911 pistols at the moment, 4 Colts and a SW1911. I consider all of them reliable, well-made pistols and have reason to trust each and every one of them. Granted, a couple of them are older models and benefited from some refinement.
I had the left side of the ambi safety on my then-new Colt XSE Government break apart and fall to the ground when I depressed the safety on the firing line during my first range session. The exposed metal seemed to make it appear that there might have been a problem with the casting of the part. The file marks made it appear as though it had taken some effort to make it fit in the gun, too.
Colt told me that this didn't happen very often with that particular vendor supplied part, but the fellow with whom I spoke didn't sound like he was exactly shocked, either. I replaced the ambi set up with a single side safety (which is my preference, anyway) and haven't had a bobble out of the pistol since that day.
As far as secondary weapons? Well, there were some instances when I was working when I carried a secondary weapon, but it wasn't as a hedge against the mechanical failure of my issued weapon. I've even carried a spare J-frame on my own time a handful of times. Very rarely, though.
Now, if you want to talk about good quality fresh factory ammunition which has exhibited a problem (hard/inert primer, short-loaded regarding powder or an improperly trimmed case) which caused a failure to chamber, failure to cycle and load a fresh round or simply a failure to fire? Hey, that can happen, too ... also not often enough to keep me awake at night.
Just my thoughts.
Frankly, I worry more about one of the tires on my motorcycle blowing out.
