Your right, there has to be a round in the chamber for the gun to fire. That said, if you are carrying a gun, without a round in the chamber, then it's pretty much worthless to you for self defense.
Can you see a woman going to her car, and being ambushed by a robber, rapist, or whatever. If her weapon isn't loaded, what's she going to do, ask the guy to wait long enough for her to both draw her gun, chamber a round, take off the safety, and then fire it. In the time it takes to do all that, she'll already be unconscious or dead.
That said, many modern guns, S&W included, offer striker fired guns similar to the Glock. One of the great things about this design is the lack of an true external safety, like the hammer blocks found on many earlier pistols. Typically the striker fired guns are safer than the others because most remain in a safe condition until the trigger is physically pulled, vs having the gun in a firing/unsafe state, but the trigger not yet pulled.
This is why Glock calls theirs a "Safe Action" design, because the trigger has to be phycially pulled to overcome not one, but three safties. They not only keep the trigger from moving until the trigger safety is depressed, they also don't fully 'cock' until the trigger pull completes the tensioning action on the striker/firing pin spring. Too, pulling the trigger disengages yet another safey by raising a spring loaded pin that blocks the striker from hitting the primer.
In the end the chance of enough things going wrong to cause one of these types of guns to fire from dropping, or anything else other than physically reaching your finger into the trigger guard, and pulling the trigger, is so remote it's not even in this universe.
In any case, situational awareness is something anyone carrying a gun, concealed or not, has to address with 100% of their thought process. Most women are so complacient with their purses when they are in a store, I'm surprised that we don't get more reports of them being stolen out of their cart when the woman walks off, turns her back on it while looking at something, or whatever.
Sadly I think that's what happened here. The woman wasn't used to the new purse she had only gotten a few days ago, and simply didn't think about what might happen. Unfortunately she paid for her lack of attention with her own death.
Glock Safe Action function