You dont here about them cause they were stopped. Its a none story without a whole bunch of blood and drama. New life church, Parker middle school , Sullivan middle school to name a few most arn't even stopped by police most end in self inflicted gun shot wounds. Im not a proponent of concealed or even open carry (with some specific exceptions) but saying that it hasn't happened is simply not true and your right its not a deterrent its not supposed to be you cant deter someone who is already at the point mentally of wanting to shoot a bunch of people , just as execution is not a deterrent for murder because most murders are crimes of passion.
But in an active shooter situation were I was not able to flee I would like the chance to fight rather than not. The police just cant respond right away and thats the reason people want to be able to carry. Statistically I don't see a need for it in this country but there are some places in the world I would feel allot safer having something (hypothetically speaking). Of course the Americas issues need to be tackled on social equality level to be effective at curbing violence with some form of additional gun control being added into the mix. (this may have an affect on the number of guns that come to us as well). But banning guns based on cosmetic features such as barrel shrouds with laws written by people who only know what end of a gun the bullet comes our of is not going to improve safety.