Food for thought -
Cocked and NOT locked while carrying in a proper holster that covers the trigger guard, most will agree, is O.K.
If you were to upholster your gun to transfer it from one location to another, would you then engage the safety until your weapon is secure again?
This is why I prefer a handgun with a safety but not to carry it with the safety on.
Guns can discharge when you're loading and unloading the chamber and when something pushes the trigger. A safety engaged would lower the chances of a discharge during these times.
As careful as everyone thinks they are, why not have that extra level of security? Why take the chance?
Obviously some guns you can't engage the safety while racking the slide, like the 1911 but you can while transferring it loaded to different locations.
BTW - My Glocks, I carry with the safeties off but I do engage them before upholstering and racking the slides.
I carry my s/a only pistols cooked and locked, but I recently started to carry my CZ 75 Compact with the safety off and the hammer down on a loaded chamber. The trigger pull has been lightened and is not much different than my Glocks now.
I know of a deputy sheriff who shot himself with a 1911 because the thumb safety was off and the strap on his tactical vest deactivated the grip safety and he somehow got the trigger pulled. I was not there and don't know the true circumstances. (I tend to be skeptical of incidents like this)
This may or may not conflict with your statement. I would say the trigger finger and the brain are the only safeties that matter.
My 1911's have their grip safeties pinned, and I always use the thumb safety but I don't trust it.