I'm not sure what company regulations banning employees from having legal firearms in their cars in the parking lot does to keep anyone in the company safe. An angry employee will just drive home, retreive their tool of choice, come back, shoot/hack/slash/blow up the gate guards, then proceed to kill anyone they choose in the buildings. You gotta bet Al Queda is aware of how nul brained we in the west are to such things and like bending over for any butcher with a grudge while at work.
What I have not seen yet, or it's quickly setteled behind closed doors with a gag order, is the employees suing the corporation for disarming them and not being able to keep anyone alive when one determined person decides to kill everyone. Gag orders and money zips lips so efficiently in the U.S., and media knowledge of the actual settelment details.
Do any of you ever ask yourselves and your employer can you the company keep me alive if my co-worker suddenly decides to use the fire ax on me, or slip a pair of sissors between my ribs, or bash me over the head with a computer chair, or smuggle a firearm past the gate and shoot me? By the level of internet obnoxiousness some of our members communicate, I gotta wonder if they don't have co-workers with morbid fantasies.
The real reason companies/corporations do this is at the demand of their insurance underwriters and lawyers. We the People don't count on the bottom line. It raises the insurance costs of doing business in any state that passes a protection of the right to keep firearms laws in your car, anywhere, anytime.
Insurance companies can afford the numbers of wrongful deaths their statistics say will happen each year if companies ban wheapons and follow insurer requirments on their properties. They don't want to get into the complicated mess of suits that can result from employees defending themselves or from employees with hoplophobia.
Bottom lines are not compatible with constitutional rights or the right to defend your life while on company property.