In the UK they are taking out those self service machines as they were losing too much to "shrinkage". I bought a single airlock from Big W the other day and had two employees on me like the CIA as I put it through the checkout.
Unless they have two employees hovering, it's a good scam to have your dizzy blonde girlfriend chuck a poor little hopeless me with her hands waving in the air and eyes rolled to the ceiling then, as the employee goes to help her with the problem you (edit: with your separate trolley of course) rush through the truss tomatoes, mushrooms and French shallotts, while conveniently scanning through the chicken wings tray with the same sized tray of Scotch Fillets stuck to the bottom.