Earlier quoted context omitted.
It's also very... American to not think mention the absurdity of machine guns at airports, even in the hands of humans. Even if lethal force is required, would you want a security person (not a trained policeman) to "start blasting" and spraying bullets with a machine-gun?
Machine guns are in a lot of airports these days, in Europe as well. It is assuredly not strange anymore (though it does come across as hostile and extremely unsafe).
What I see now is occasional police officers with their standard sidearms, but rarely see anyone more armed than that.