While a new [Senate] inquiry looks set to examine [Coles and Woolworths’] profit margins, New Zealand offers a lesson in just how difficult it is to disrupt a duopoly. [They have] no Aldi or IGA, and the duopoly there has also faced allegations of price gouging.

The New Zealand competition watchdog has already held a market study into why food costs so much in Aotearoa and established a grocery commissioner to help implement its recommendations.

But 18 months down the line, Kiwis are still reporting their grocery bill as a major financial concern — for the first time, some families are struggling with the cost of putting food on the table.

Based on this experience, advocacy group Consumer NZ said an inquiry could be helpful to establish the facts around whether or not supermarket giants were making more than what was fair.

But they warned the process was slow, and ultimately if it did not lead to bold changes, the business of selling food to Australians was likely to continue being a very closed, and expensive, shop.