and a gun carrier comes up behind me.
I would walk away telling him I don't want to be shot and leave the basket where it is.

If they are not one the next thought is a fearful, unsocialized soul who should just stay at home behind his ADT system and his arsenal.

easy enough to spot and avoid, but concealed carriers who are idiots are more problematic. In many "shall issue" jurisdictions almost anyone who hasn't had a parking ticket can get a CCW in short order, and this includes drunks, abusive sociopaths, bullies, and other anti-social misfits.

The gun culture mindset that a lethal weapon is an "equalizer" and a personal problem solver too often results in a permanent solution to a temporary problem. While CCW holders claim to be more upstanding and law-abiding than most Americans, those claims do not take into account someone's personal character. Being an anti-social asshole, a bully, and a paranoid coward should be a valid consideration when it comes to someone being given the power to take a life based on feeling threatened.

Police officers and other professionals who carry weapons in public as a part of their duties are given psychological evaluations and extensive training before being allowed to carry a weapon in public. Why not apply the same standards to anyone who wishes to carry a weapon in the public venue for no apparent reason, but supposedly for possible self-defense "just in case I'm threatened?" That amount of paranoia would seem to be a cause for concern right from the outset.