Well I don't agree with shooting someone over a 15.00 theft. Often times if a shoplifter is "caught" stealing just outside the door you can get them to come back and pay for the item they thought they "slipped out with".
But doing this has a risk that they are high on glue and are not thinking clearly and will stab you to death for the case of beer. So you take a pistol along with you, and when they do try to stab you to death over your case of beer you shoot them. Then the media comes in and say you chased them down and shot them for 15.00 in beer.
Oh and add to this that the thief could be underage and when caught drinking your stolen beer will blame you the shop owner for "giving them" beer and you go to jail for it.
Everything is more complicated in real life.
Castle doctrine never gives you the right to shoot whoever whenever, we all know this.