Not only the check writer, but also the customer (usually an older woman) who, after the clerk has rung up and bagged a $125 order of groceries, suddenly remembers she has to pay for them and starts rummaging in her purse for the card or the checkbook. Then there are the types whose cards are rejected or can't remember their pin and have to get the manager over to clear up the mess.
I recall when the scanners first went into operation, the prediction was that customers would soon be able to wheel the buggy through the scanner and all items would be totaled automatically with no human interaction. Whatever happened to that?
The Beast hasn't yet gotten everyone to have a number on his forehead or right wrist. . .