They generally don’t. I’ve worked in retail in places with security and without, and generally we aren’t able to catch people stealing things in real time.
The way stores find out how much stuff is stolen is through periodic audits. We print out a list of everything we should have in stock according to the computer system.
Then the associates go around the store and look for it and scan it. Then they run a comparison of items scanned vs. items that the store should have in stock.
The difference is loss which is due to either theft or breakage (some items get broken and aren’t properly zeroed out).
Those machines are more savvy than you may think, too. They talk some robot nonsense and shut down regularly, needing human intervention. But I was stunned recently when I inadvertently scanned one product that had another identical stuck to it. (light plastic crockery) When I placed it in the bagging area, it sensed •double weight• and wouldn’t process my next item until I ‘unstole’ the $2.50 product.
On a larger scale, they can compare the totals of all items sold to the items that must be purchased to restock. It doesn’t prevent individual thefts, but it does present the total loss, which the store decides is either worth it or not.
There was a grocery store in the UK that discovered widespread fraud when their computer told them to order a massive quantity of carrots to replace the carrots sold, but the carrots sold was greater than the amount the store had in the first place. Turns out people were buying expensive produce, putting it on the scale, and telling the computer it was carrots, which were much cheaper. So the computer sees 5 pounds of something go on the scale, which the customer claims is carrots, then it sees those 5 pounds come off the scale and reappear in the bagging area, and all is well. They don’t discover until later that it was 5 pounds of dragonfruit (4.99/lb), and not carrots (0.49/lb).
If you’re planning to try this method, I recommend that you buy the “Organic” produce and ring it up as the “regular” produce of the same type. Much easier to claim as an accident.
I accidentally put two things in my bag after only scanning one of the items in my hands at a store a couple months ago. There was a camera on the self checkout and it froze the transaction immediately and sent an employee over there by way of flashing light. It gave an error that there was an unscanned item in the bags and the employee had to unlock it for me.
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