It is a mechanical thing. Although I am a fan of the transfer bar it still is mechanical and subject to faults and failures. Depending on that 100% for safety is not wise, IMHO. It SHOULD protect against unintentional fire. I disagree that one must have his head in the clouds for an unintentional cocking while in the woods. It happened to me during a deer hunt with a SA revolver that did not have a transfer bar. I didn't discover it until I was back in camp. I later switched to a full flap for that gun. For my SS I made my own holster that covers the hammer but is still open top and easily accessible. I often wonder why commercial holsters are not offered this way. Great design, if I say so myself.
Oops, pic didn't attach. Try again.
Apparently the forum will not allow posting of a pic more than once. The holster link can be seen in this thread: