Warned by the questions fired at his peers to be prepared to talk about credit card profits, Hartzer insisted that his bank "does not even have a credit card business."He explained that costs (from branches, back office, IT and head office) were just too hard to allocate.Hartzer did allow that the bank could work out a form of economic profit.Pestered to consider whether it may be viable to lower credit card rates and for the bank to be profitable, Harter clarified."I agree credit cards are profitable," he said.A sliver of cost insight emerged on a related topic when asked to state the cost of running an ATM network.Hartzer said this was 20 cents per transaction. He did not add this is one tenth of the convenience fee charged by Westpac to any user of its ATMs who hold a bank account elsewhere.Labor MP Matt Keogh then asked for marginal cost, Hartzer's non-answer wandering over the numerous costs of running the fleet, cost not fully covered by routine account fees incurred by its own customers.On one more theme pursued with all CEOs, account portability, Hartzer said "it's an important issue ... we don't object" but stressed it is "a lot harder than you think" and some facets of any industry-wide model would be "unbelievably expensive" and "technically complicated".Hartzer insisted switching accounts is simple. "You can switch to Westpac in ten minutes online," he said.