There's a great disconnect between actual security needs and the security theatre demanded of those who must engage in guard duties. Those in charge must view the empowerment of security guards to determine actual threats as somehow inviting disaster when in fact, it may reduce the significant bureaucracy and paperwork these "centralised evaluation" procedures may impose.
I'm afraid to say that I'm worried that the more power you give guards to determine threats, the more they will harass folks. There is a bit of a ratcheting effect, no one will get in trouble for being too strict, but you're likely to get in trouble if you miss something, but there's also the human love of power in there. Give people power over a limited domain, and they just love to wield it.
