What they do is swap bar codes, or they code organic fruit as regular, or they "forget" to scan in the self checkout, but yes.
This is a big reason why retail product barcode stickers (not barcodes printed directly on a package as it comes from the manufacturer) are now commonly printed on frangible stock with built in slices in it which breaks apart in 3, 4 or more pieces if you try to peel it off.
So it's just stealing with extra steps.