THE DAILY CHART: RBA's bank bashing spoiler

It's not very sporting of the Reserve Bank to tell Canberra that the latest round of bank bashing is effectively baseless but that's pretty much what it's done, albeit in its usual subtle fashion. In its submission to the Senate's inquiry into banking competition, the Reserve Bank says net interest margins – the mortgage lending profit margin – have "fluctuated within a relatively narrow range between 2.25 and 2.5 per cent". During the global financial crisis net interest margins fell to the bottom of that range and since then they've risen to the top. If the bank bashers were really looking for evidence of gratuitous mortgage rate gouging, they'd find it here.

As Stephen Bartholomeusz points out, the Reserve Bank's submission "supports the majors' claims that the increase in their funding costs bears no meaningful relation to movements in the RBA's cash rate and that their average funding costs are still rising." But bank bashing is not without political consequence. Mortgage holders like it, because it's hard to be told that mortgage stress is the result of a collective home-ownership desperation that's forced us all to borrow to our limit – no, you're being screwed on your rates. For non-mortgage holders – the more passive bank bashers – they'd have enough poor experiences with customer service at the big four to appreciate Canberra's crusade without caring about the fine details. Which isn't entirely unfounded, not even the RBA could deny customer service at the banks is atrocious.