In traditional banking, we may see the very basic, real-world, model that all these systems are trying to emulate. Customers perform secure transactions with the bank in a controlled and secure environment.

The back-end system takes cash inputs and outputs, storing and retrieving the cash from a secured location ("the vault"). Cash is counted and accounted for in every step of its journey through enough hands to make it impossible to steal without conspiring with others. The front-end, transaction processing system consists of a "public" area, a "teller" area, a "back office" area and a "vault". All areas are under video surveillance, alarm systems are used to enforce hours of operation in different areas, humans are fully aware of what is going on and responses have been crafted for any significant threat to the security of the transaction or the customers and their accounts.