Doing this in a gunfight at 3 or 4 feet is simply suicifal.
What kind of "gunfight at 3 or 4 feet" would you be in where you didn't intend to fire? The rule says you keep your finger off the trigger ONLY if you "don't intend to fire".
John, that you would find unacceptable a condition in a new automobile that would make it more likely that momentary inattention could result in injury is exactly the point being made.
I've never seen a car in which momentary inattention was safe. I see a lot of drivers who apparently don't feel that way but the fact is that in any automobile or with any firearm, momentary inattention can result in injury.
We also know that reasonably competent people who exercise ordinary care and normal attention still have lapses and accidents.
You're playing with words. First of all, what do you mean by "
reasonably competent"? Is that someone who only knows some of the gun safety rules or someone who only follows them some of the time?
The bottom line is that a person who doesn't know or doesn't follow the basic gun safety rules when handling a firearm is not using "ordinary care, normal attention and reasonable competence".
YES, people can have lapses--it happens, and not just to people who have guns without manual safeties.

But when it happens, it happens because of the lapse, NOT because of the gun.
Luckily most engineers are smart enough to understand people aren't perfect. There is a great deal of effort put into designing products that account for the fact that all humans are fully capable of error.
As an engineer, I agree with this. But you have to decide WHERE you want to draw the line. You can try to eliminate every possibility for human error in which case you typically end up with a product that is difficult to use and/or prone to failure. An example of this is my microwave oven. It has multiple safety interlocks in the door to prevent operation with the door open. Not one, not two, not even three. One of them broke and rendered my microwave useless until I was able to repair it. That's not the kind of thing I want happening with my self-defense firearm.
As an engineer, you are aware that everything is a compromise. If you want one feature you must trade something to get it. Cost, complexity, reliability, durability, manufacturing complexity, ease of use, weight, etc. For every plus there's a minus--that's a basic principle of engineering design. But somehow in this thread you're arguing as if it's possible to eliminate the possibility of human error without it costing something else of value.
One must strike a compromise between making something that is simple and reliable vs impossible to make a mistake with. Given the extreme simplicity of the basic firearm safety rules and their UNIVERSAL acceptance, it's reasonable to design a gun such that it will be safe if those
universally accepted rules are followed.
Furthermore, given that
all guns are unsafe if the basic rules are NOT followed, it's hard to argue that a gun that is obviously safe IF the rules are followed can be called unsafe.
So... Are Glocks unsafe? Hell no. But does anyone really believe they are the absolute safest design?
This is getting to the heart of it. I'd go a step farther and ask what IS the absolute safest design?
If you're in a gunfight and are injured such that you can't properly grip the gun and the grip safety is not operated, that's pretty dangerous--a gun without a grip safety would be safer. If you drop a gun with no manual safety and make a grab for it, that's pretty dangerous--a gun with a grip safety would be safer. You have to pick which situation is more critical in your opinion (and/or if you can ameliorate one situation with training--like training yourself NOT to grab for a dropped gun, for example) and make your choice. Fortunately you CAN make a choice because the variety of firearms available to U.S. citizens is amazing. Whatever you decide, it's out there waiting for you to plunk down your money.
Yet, a pistol which requires a holster as a safety device is not one I wish to own. You cannot carry a Glock safely in just any old holster. That is what I consider a design defect. Did they intend it to be that way?
YES, if you notice, Glock is one of the few gunmakers who makes holsters for their own pistols. The holster is part of the safety system. HOWEVER, if you don't like this feature then you shouldn't buy one--just as you say. That's the beauty of it--you don't have to, there are many other guns out there for you.
It is my opinion that GLocks, like landmines, should not be left laying around one's home or person waiting for one to make a mistake and "step in the wrong place."
Again, this is overly dramatic. ANYONE who knows and follows the BASIC gun safety rules can safely handle a Glock. It's that simple. They're not pit vipers waiting to bite the unsuspecting, they're not landmines that will blow up if stepped on, they're guns, and like any other gun, adherence to the BASIC safety rules will allow you to handle them with impunity.