It will store personnel forgetting to remove or in the process of removing labels on the shelves. With weekly specials or changes in pricing, staff having to manually remove labels on the shelves and place any new ones quickly (needs to be done from 23.59:59 to 00:00:01 in the case of 24 hour stores). In reality, it can take hours to relabel shelves within a store with price changes and new weekly specials.
If one shops early on the day that the change comes in, it is possible to in some circumstances to ‘game’ their shelf labelling by buying with an old shelf label before a new one has been inserted. The electronic pricing seen at the supermarket is pushed out overnight, but shelf labelling can lag behind.
With electronic shelf pricing which is likely to be rolled out in every store in the future, the opportunity to exploit any discrepancy in pricing/timing will disappear as these will be updated quickly (within a wink of the eye when the prices change) and at the same time as checkout pricing.
