I witnessed a beer run a couple of years ago. I had pulled up to Circle K and let a friend out, while I waited in the car. A few seconds later, a teenaged girl came RACING out of the store with a case of beer, ran around the corner of the building, and hopped into a waiting car to speed off.
I kind of laughed, and thought you must have to be very brave or very desperate to try it, then thought nothing more of it - until a couple of weeks later when I read that a clerk at a different store was killed trying to stop a beer run.
You never know when crime can rear its head, and - like you - I believe that being prepared is the best policy. I think if more of us carried more of the time, there would be far less "crime of opportunity" out there.