I'm kind of with the OP here. Check the damn chamber. I check the chamber every single time I handle my gun, even if I "know" it's unloaded (or loaded) If you don't, well, at least there's the other firearm handling rules to follow before take down. If you (or someone else) are shot disassembling your Glock, it's not just one rule you broke, it's a bunch.
Ok, so taking the firearm down required you to pull the trigger. So, by necessity you have to break rule #3. But, what about #1? That one was broken, since you didn't chamber check. What about rule #2? Why was the muzzle in a direction that isn't safe...ESPECIALLY WHEN PULLING THE TRIGGER ON A GUN!!!!
I feel bad for the guy in the story above, but he was extremely negligent. It was not the fault of the gun. It was the operator...plain and simple. According to some people posting here, we shouldn't do dry fire practice in our homes because it required us to pull the trigger. Yet every expert shooter out there says that dry fire is needed to build up and work on skills.
There are almost zero cases of a true accidental discharge. Nearly every single one can be boiled down to gross negligence of the operator, regardless of gun design.