>>64496583
It's based on who the customer is. Different orgs have different requirements on who they want on contracts. The contracting company for the most part just wants to fill the slots to make money. More premium gigs have harder selections and pay more based on the fitness, shooting, and clearance requirements.
When you read stories of security guards and non-tactical backgrounds working contracts during the early GWOT, it's because they were likely on smaller gigs that didn't have hard requirements from the client on who could staff it. DESU, even if this were to happen again I'd be sketched out working out for such a company. Look up Custer Battles or the book, "A Bloody Business".