I know logic just does not seem to be the absolute truth when dealing with humans.
How many people would still be alive if there were some type of very visible way to double check. (ok, say all guns were made with clear plastic and you could actually see the bullet in the chamber)
I don't know the stats, but there would be a lot.
And no one has ever pressed the gas when looking for the brake in a car and ended up running people over!
People make mistakes and the things we design (I am a designer) should rule out the possibility of making the mistake. That is good design.
I was brought up around guns so it is second nature, but people who have not just forget sometimes.