Responses
Well, nobility and status matter only for conventional businesses carried out in the open, but the underworld has its own hierarchy and rules of engagement. Noble status and the official titles of mainstream society aren't in themselves worth much for the "businessmen" of the covert underworld, where the only authority anyone has is the one of a paying customer: the degree of authority depends on the amount of money they are each willing to pay out.
Why people who has lower status than the Duke, act like that towards him. Just don't like the characters who act like that towards Hexion. Special mention to FL's annoying step brother.