Actually some do. I have.
The challenge is not to be anywhere near a anti gun, anti carry state. The employer can always fire me. But some parts of the USA I refuse to go unarmed been licensed for many years. No trouble.
Employers bleat so much. I think back to the old days years ago and think in amazement how I got away with going into some places. I remember a few times I would have a holstered knife, a buck special on the open carry off the belt in Kennedy Air Cargo. No one cared. Its for baling wire and pallet nets etc. Slice slice.
That and a chain drive wallet. Pretty much kept the bad guys from bothering me too much.
Today? Heh.