This WSJ article really slams the self-checkout machines at the supermarket, primarily because the customer has to use the screens to look up codes for various fruits and veggies. I find this process to be remarkably easy myself, and always use the self-checkout line unless I have too many groceries to fit on the tiny shelf.
In my opinion the author misses the primary benefits of the self-checkout line.
1. Usually people form a single line that feeds into multiple machines. With a human cashier you have to take your chances in a line that feeds to a single register. Even if some customer fumbles and stalls you won't be stopped for long because one of the other self-checkout terminals will open up.
2. Everyone pays by credit card. The machines appear to have many payment options available, but I never see anyone try to pay by check or food stamps or cash with exact change.
3. The lines never get held up for price checks or because the customer forgot to grab something.
I agree that human cashiers are better than the robots, but human customers are often terrible. Self-checkout lines repel the worst customers.