I heard an interesting report on Marketplace on surprises in the self-checkout lane. Impulse buying is down, and stores have come up with other ways to entice you into buying something you hadn't planned. And it turns out that fears from retailers that customers would cheat at the self-checkout turned out to be misplaced:

The reality of the situation is that most losses or theft come from the employees themselves. One of the things that we're realizing is actually that customers are more honest than the people that are working there.