Self checkout doesn't save them money - it costs them a great deal because of thieves like Hancock27.
Just yesterday, I went up to a self-check machine and there was a payment due total displayed. That means that previous low-life went through the motions of scanning stuff and then just walked off with it all. I alerted the poor woman who was monitoring the machines, and she mumbled something like "another one." I hope that those workers don't get dinged for not catching thieves.
Karma can be a biottch
I'm a believer