That said, modern grocery stores have structured the self-checkout aisles so that one or two employees are always watching and are directed to "help" any shopper who omits an item while checking out. Also, you may note that the "10 or Less" aisle is strategically placed right next to the self-checkout aisles, and that "10 or less" aisle is primarily reserved for people who have been directed over there by one of the two staff people. That is, if someone may be a thief, staff members are instructed to invite them to use the "10 or less" lane even though they have more than ten items. It makes people feel special, and also cuts down on self-checkout robbery. There are multiple cameras trained on that zone in the store as well.

On that note, I once grabbed a "Valentine's Day" balloon for my girlfriend over in the flower department and I honestly thought it was free because the store had them scattered all over the area. I did self-checkout, and was gently "offered assistance" so as to also pay for the balloon.

(http://www.autoadmit.com/thread.php?thread_id=5744511&forum_id=2E#49059854)