It does not seem worth it. I purchased a $15 drain pipe from Home Depot and had placed a $1.49 end cap on it so my purchase came to $1.49 and not the $16.49 it should have. I caught my error and paid for both. But had I followed thru, they would have had me on video. Not fast forward a few other suspicious transactions and one day you actually are busted. The store will have a collection of video evidence that clearly allows them to distinguish your actions as not simple mistakes. So I think anyone could do this once or twice by accident. But the risks vs reward issue seems very high for multiple thefts as when you are eventually caught. They can pull up all your recorded credit card transactions and quickly build a case.

The machines can be buggy. The one I use (Giant supermarkets) often doesn't ask for a quantity on navel oranges. It just rings up the the price for one and says put them in the bag. I don't want to bother the attendant, who's often busy debugging some problem another person is having, so I just put them in the bag. I've probably not paid for a few 10s of bucks on navel oranges this way over the past few years.

The anti-theft system is pretty paranoid though. I've tripped up its video alarm a few times just with my normal awkward motions - waffling about which item I want to scan next, while holding it, seems to mess it up. The attendant comes over and we both watch the review video from the camera above featuring a few seconds of my receding hairline, he clears it and I keep going.

But I still prefer self-checkout greatly over weird/awkward human interactions, and I can bag at my own pace too and i'm not holding up the line.