The cameras are there because people regularly abuse the system and steal items. You may not be a criminal, but blame the significant percentage of your fellow men and women who have no qualms about stealing items from a store for the fact that everybody gets watched. Shoplifting costs businesses a not insignificant amount of money each year and the rest of us pay for it in higher prices. All self checkout systems have cameras, if not in the unit itself, there are surveillance cameras in the ceiling above. You're on someone elses private property, there should be no expectation of privacy.