You seem them everywhere. They are in shopping centers, at banks, and any large public event. They are people with no real power placed to make the dumbest 5% of criminals think twice, and make the most ignorant of consumers feel slightly more safe. They serve no real purpose, and aren't good for much. It is a job with no real point, that is given to people with no real other option.
The people that work as security guards fall into several categories. First there are the ones that think one day they will become police officers, they won't, but it is good they have a dream. Then we have ones that are just not cut out for anything else, too dumb to operate a register, too clumsy to be a stock selves, too ugly to get by on looks. Last we have the failures, ex cons, dishonorably discharged, dirty cops that got caught, and whatever other breed of loser you can imagine. All three of these groups doing what they do because they aren't bright enough for anything else. They are too dumb to see what ISN'T in their future, too dumb to have avoided getting caught at their first choice, or just too dim for most things period.
Security don't really serve much of a purpose. No one serious about committing theft, or any other crime, has ever been scared off by the presence of a security guard. They have no real authority to do anything. Sure they look something like a cop, kinda, if you don't get a very good look at them. In the end they are space fillers, and having them on the payroll is making every item in the store slightly more expensive.
The average security guard is sad, lonely, and likely suicidal person. You don't need to pay them much attention, but don't openly disrespect them. Instead just steal what you want, and give them a smile. We can always be civil.