The self checkout at my preferred grocery store (Hy-vee, an upper midwest chain) has started using these overhead cameras to confirm that you're purchasing everything you ostensibly have in your cart. Except it always flags us for the Starbucks drinks we're carrying (Hy-vees usually have a mini Starbucks shop inside them). More annoying though is that it flags us for the 5 gallon water jug refills that we manually punch into the self-checkout kiosk, because the surveillance system isn't satisfied unless the heavy ass jugs of water leave the cart, slide across the scanner and then get placed in the bagging area – anything else is possible theft.

All this has done is train us to keep the carts out of the camera's viewing angle. It doesn't care if you keep pulling handfuls of groceries out of hammer space, as long as there's no cart in the frame.