I think it is unintentional at best and laziest at worst. It is likely that the operator of the labeller would have a choice, but maybe they don;t know how to change for conformity or couldn’t be bothered as near enough is good enough…and as long as it has something, all is sweet.
I would have thought in today’s day and age that the main computer system would generate a batch file of labels for printing/dispensing and placement in store. If this is the case, then it is likely to be intentional as the retailer would be able to set the unit price before generating the label.
Unfortunately, it is my first thoughts which I think is possibly more likely.
Maybe Choice could ask/survey the major retailers how they set the unit prices shown on labels in store:
Set by a master whole of organisation controller
Set on a store by store basis
Set by the operator of the labeller/label dispenser
The other question of interest would be what measures do they implement to ensure consistency.