I know for a fact that the company I work for bans weapons even to the point of company cars. They consider the company cars, company property and extend their weapons ban to all company property. :-(
I think that most major corporations bad weapons by employees if for no other reason to appease the lawyers and avoid any lawsuits. I also think a large subset of those ban weapons on premises (non-employees) but have no real data to back my "opinion". As a consultant, every customer I have been to has some restriction (usually a total ban).
Virginia is a pretty good state for OC but multi-state/nation corporations probably sink down to the lowest common denominator as far as policies. It is actually refreshing when you hear of places like Starbucks and Walmart that follow state law "as" their policy rather than defining something anti. Again any pro-2A-policies tend to only apply to customers not employees.