Coles has been at the forefront of a media campaign with the police this week to stamp out the apparently dire menace of people potentially shoplifting while using the self-service lanes at their supermarkets.

They somehow managed to simultaneously wag their fingers and shake their fists at us all for being so devious and opportunistic. One detective solemnly noted that even if you were saving $2 on an avocado, it was still shoplifting.

This terrible campaign is designed simply to make innocent people feel like criminals. And it disregards the fundamental golden thread running through our criminal law: the presumption of innocence.

Without consultation, supermarkets have taken away manned checkouts, thereby cutting their costs. They then make us, their supposedly valued customers, responsible for doing a huge amount of unpaid work, correctly scanning items. Then they castigate us if we get things wrong. Meanwhile the costs of the police and the prosecution of shoplifters are borne by the public.