I'm afraid BB can't stand hearing other opinions than his.
The mechanics of the inner workings of the Glock pistol are facts, not opinions.
In my humble opinion a single action (striker fired) gun...
Single action and striker fired are two totally unrelated things.
...can only be cocked by racking the slide and not by pulling the trigger, as is the fact for all Glock pistols.
Racking the slide simply chambers a round and resets the trigger. The firing mechanism is blocked and under no load until the trigger is depressed, the act of depressing the trigger draws the striker back on it's spring (cocking). Hence, it is not a single-action trigger. The action in a Glock can not be considered single action, nor double action. Hence safe-action.
Once released the striker can not be cocked with a double action trigger pull like the double action striker fired Walther P99 (better check and upgrade your basic knowledge on inner workings of various guns BB !).
What does a Walther have to do with it? I made no comment in regard to a P99, as I know nothing about them. I don't make statments about things I don't understand. I do understand Glock pistol design, which it is clear you do not. Safe-Action is made up of three seperate safeties, not just the trigger safety. The three safeties are-
1. Trigger Safety:
This is incorporated into the trigger in the form of a lever and in the untouched state it prevents the trigger from being moved rearward. If the weapon is dropped or if the trigger is subjected to an off center lateral pressure; the trigger will remain in the forward locked position. The trigger safety can only be released by pressure being applied directly to the lever on the trigger. This type of safety, in conjunction with the other two, offers a minimum fire ready time with a maximum level of safety for the user.
2. Firing pin safety:
In the secured position, the spring loaded firing pin safety plunger projects into the firing pin channel. This prevents the firing pin from moving forward, until the trigger is depressed.
3. Dropped gun Safety:
The firing pin pushes the trigger bar onto the safety ramp of the trigger mechanism housing under the power of the firing pinspring. This action places the left side extension of the trigger bar cruciform (the gun oriented with the muzzle down range) on the trigger mechanism housing ramp until the trigger is fully depressed. This safety prevents the trigger bar from releasing the firing pin without the trigger being depressed. If the trigger bar does not drop, the firing pin is not released.
So, in answer to your question "...and this is the fundamental issue : since when can guns fire as long as there's no pressure from the trigger finger on the trigger?" I would say in the case of a Glock, it can't. Fire that is. There MUST be pressure on the trigger, it CAN"T fire if there isn't deliberate, centered, rearward pressure on the trigger.
PS-The only money I've invested in Glock is what I've spent on the ones I own. I realize there are limitations to the design, and improvments can be made. I am not a "Glockhead", as I do realize that they are far from "Perfection". What I can't stand is when people who have no knowledge of a subject making false and uninformed statements on that subject. If you can't handle the responsibility of owning a Glock, great, don't buy one. But I would seriously wonder about the competence of an individual that couldn't handle said responsibility as it pertains to any other firearm out there.