This might work better for a library than a for-profit institution like a grocery store. I imagine that self checkout doesn't get all that many cheaters becaus

This might work better for a library than a for-profit institution like a grocery store. I imagine that self checkout doesn't get all that many cheaters because people think there are cameras, and being busted for stealing is a pretty humiliating big deal most people wouldn't want to risk, even if the risk is small.