Mostly it is knee jerk reaction by people whose gun knowledge comes from the internet. I love guns with redundant safeties so I can choose to use them or not. Most of my guns have hammers and safeties. Many will say that it is possible that your safety can engage without you knowing it. It is also possible that Pam Anderson will marry me and we will honeymoon in my yacht in Monte Carlo. A lot of things are possible but unlikely.
Your brain may be the most important safety but unfortunately it is not the best. If it were we would not have so many safety devices in our lives and would not be reading about so many unintentional discharges. We are human and therefore subject to mental errors and those who cavalierly say keep your finger off the safety should check to see how telling someone to drive safe works.
I have been shooting over 40 years and know that if you handle a gun a lot, especially under stress in a non static environment, you probably fired your gun before you ready to. It may just be downrange or it may be in your house while dry firing. At my old gun club we used to say that if you have not had an unintentional discharge, you are not shooting enough. We also divided shooters into those that had an AD and those just waiting to have one.
A safety is not a safety if it does not prevent you from doing something you should not do. In this case, pull the trigger until you are ready to. The safeties in a Glock and others are there, not for our protection, but for the protection from liability for the manufacturer. They save a lot of money by eliminating a manual safety and then get people to accept it as a good selling point.
Just think about it, the same people who are afraid that they will forget to disengage a safety are telling you not to forget to keep your finger off the trigger. Huh? Isn't it not the same to remember either one of them? In worse case, having used a 1911 in combat, you quickly recognize that you forgot to flick the safety off safe and immediately remedy that in the next second. If a second or two is that critical you have failed to use your mind, the same one that is supposed to be your best safety, to be situationally aware of your surroundings and allows someone to get that close to you. People worry about any stupid little thing simply because it is possible rather than because it is likely. I can be hit in the head with a meteorite which is a real possibility but it is highly unlikely so I choose not to wear a helmet when I go out.
