"Please scan your first item," the machine says in its cold semi-human voice. John glares at it, hoping against hope that it won't be a repeat of last time. The biscuits scan alright, as do the milk and Sherlock's nicotine patches. But then he gets to the fruit and it all goes horribly wrong.
The pears won't count correctly as he weighs them. The apples are overpriced—the machine has for some reason not been updated with the sale price. The computer keeps shouting at him to put the solitary plum in the bagging area, even though he's already done so, and the entry for the kiwi fruits was completely absent. He resists shouting at it, as it was embarrassing last time, but he just can't help it when he goes to pay for the groceries.
First it wouldn't take his cash—the bills were too wrinkled or something. Then his card wouldn't scan properly (it was worn out.)
"Just take the damned cash already!" Already the people behind him were staring. He was getting flustered and embarrassed and was sorely tempted to shoot the machine except that for one, he didn't have a gun, and for two, he would have been arrested. Fortunately, the woman behind him in line was kind enough to swap his somewhat tattered bills for her crisp, clean ones. Then the machine took it.
But then, of course, the shoplifting alarm went off as he left the store. John hated technology.