You're right.
But I can tell you that I did receive some training by a very reputable climber (who shall remain anonymous) and during the demonstration of fall protection caught his own mistake of a screw gate carabiner being all the way loose instead of tightened.
If a seasoned climber can screw it up (no pun intended >>> no, really!), then I surely won't trust that piece of gear. Ever.
No record of an accident caused by this = it's never happened ???
I'm not sure I see your point, Teresa. If the expereienced climber caught the mistake, then his system of checking his fall protection before use worked as it should. He didn't screw anything up, he checked and corrected it, or am I misunderstanding?
And if you or anyone else thinks that by using an autolock biner you have either prevented the possibility that it will fail to lock, or that you have made it such that you no longer need to check the biner each time you use it, you are sadly mistaken.
In an agency climbing program as heavily controlled as the USFS one, I am pretty comfortable saying that if it was not reported, no climber was injured or killed due to a biner failure. Sure, it might happen, but so many required things would have to NOT happen for it to slip by that it gets to be a tiny possibility.