Right. Just like a seat bealt and an airbag.
Bad analogy is bad.
With a gun, as long as you
keep your finger off the trigger until you are ready to intentionally fire, you will never have a negligent discharge. A manual safety is unneeded. If it makes you feel safer, so be it, but it doesn't actually make the gun safer.
With a car, even if you're the best driver in the world, you still have to worry about all the other
drivers. Because of this, seatbelts and airbags actually do make a car safer.
Your analogy would work if the safety on your gun could keep you from getting shot unintentionally by someone else with their gun. Unfortunately, that's not the case, and why your analogy doesn't work.