What many employers fail to comprehend is the fact that those who possess a permit to carry are the "good guys". They have been vetted by the local police or sheriff. They have NO criminal record. I would like to see a law on the books forcing companies that forbid the legal carry of firearms at the workplace, or store, mall, etc., be required to accept ALL responsibility for the patrons or employees safety.
That's not the way an employer looks at it.
They're looking at it as an entity that can be sued for an employee's behavior no matter how justified.
They're looking at it as a possible PR nightmare if some over-reacting customer sees their employees walking around strapped.
They're looking at it with the mindset that if they condone such actionsr they encourage it and some employee may be capped off trying to play Charles Bronson.
Their motives are not ignorant, unfounded or malevolent. I genuinely sympathize with them because their concerns are sincere and well-illustrated by past events.
But that doesn't mean I agree with them making zero-tolerance blanket policies. They should judge on a case-by-case basis.