Regarding the negligent discharge that took the life of a concealed carry holder in Spotsylvania County this week, it looks like the man was not carrying his gun in a holster. That is a really dangerous thing to do, especially with a striker-fire autoloader such as a Glock.
I will admit that I have, on occasion, taken my XDm and placed it in my waste band in the small of my back when I'm around the house. But I never sit down, much less get in my car with it like that. Additionally, an XDm has a grip safety which Glocks do not.