Or go off half-cocked.
Personally, I would not carry a Glock w/ a round in the chamber unless it had a New York trigger. aka approx 10 lb pull.
I prefer Sig DA/SA, I also don't front carry.
I've carried one for about 15 years without a Negligent Discharge. The first major rule about Glocks is that you ALWAYS ALWAYS ALWAYS carry one ONLY in a hard holster, so that there's no way the trigger can be touched before you deliberately withdraw it from the holster. The second rule is to carry it on your hip, so that if Mr Murphy visits you, the negligent discharge only grazes your buttocks or leg, rather than performing an informal sex change operation.
This guy violated both rules.
I carry a KelTec P11.
It has no safety. The long 8 lb. trigger pull is the safety (other than the one between your ears).
I carry with a round chambered at all times. Like a previous poster said, you should carry them in a holster.