Try to prevent clients from walking out of your retail outlet/store with product which they have not paid for.
Shop lifting is a common occurrence.
Clients will enter a store with a container of some sorts, e.g. the empty box for a printer cartridge, the “reason” being that they need to get another and want to make sure that they get the correct item.
They then walk out of the store, claiming that they brought it into the store.
Some retailers use “stickers” to identify the items which are brought into the store, but many of these can be transferred onto another package.
The criminally inclined shoppers will then transfer these stickers onto another item and carry it out of the store, with the resultant loss to the retailer!
We have "stickers" which cannot be transferred.