If you've been to any major store chain in the US in the last year, you've probably seen one of the self checkout lanes that have been installed in most of them. Have you ever noticed that about half of them are always closed?
What's the point of spending all the money to retrofit the stores and install these computers if they're not going to be used? People hate to wait in line, so why don't they turn on the self checkouts instead of letting them sit there when the lines are backed up to the wall?