"Only when prats arrive with vegetables that they haven't created a scanning label for..."
And presumably those that they have not been down to the farm for and dug up themselves!!
The answer to this is simple. All shoppers should simply boycott these machines (which seldom seem to work properly without intervention), leave them idle and lobby the stores to introduce a proper checkout system where people are assisted with their purchases. My local B&Q has a habit of providing these machines as the only checkout option for long periods of the day. Whenever I shop there when this is the case I ask the staff if they will open a conventional till. If they will not I seek out the manager, give him my goods to return to the shelves and simply inform him I will not shop in his store whilst he fails to provide proper staffing. It's no good moaning about these things; only when people in sufficient numbers do something about it will matters change. If you're not prepared to do that you will just have to put up with it because big organisations will get away with whatever they can to increase profits.