If you have to explain to a professional that is employed to enforce the law of the land, we're screwed. And the employee that doesn't know his job needs to be gone.
/johnny
LEOs have to deal with a lot of liars, scoundrels, and normal, polite people every day. So it’s pretty typical that the first thing they do at a scene is to scope out the people, and figure out who is what.
The fastest way to do this is to look for attitude. They have no miracle ability to tell what’s going on just by looking, so it should be no surprise that if you act like an aggressive dork, they will treat you like one, without further adieu. What the law says at that point is kind of secondary, and only comes into play when they know where they stand.
So being friendly, forthcoming with information, etc., helps the LEOs to get on to the legal part sooner, rather than later.
As far as store employees go, they are just minimum wage types hired to do minimum wage stuff. That’s all there is to their job, unless they are taught otherwise.
Maybe they do know and just want to harass people who carry. More and more the cops are nothing but revenue collectors and the local enforcers of leftwing policies.