You can only cut so much labor to 'save costs' before you start losing business the way Walmart was because people were getting pissed off by the long lines and slow checkouts(among other things).
I visited Santiago, Chile, a few years ago. Chile has a decent economy and a standard of living generally on par with the U.S. They have a chain of stores somewhat akin to Super Wal-Marts, called Jumbo. Jumbo is a bit heavier on foods and a bit lighter on clothing and toys, but generally about the same size as most Super Wal-Marts I've seen.
Other than at Christmas, most Wal-Marts I've been in rarely have more than three registers open, regardless of how long the lines are. The automated lanes are always open, of course, yet people are lined up at the manned registers while the automated lanes are empty. You might think the stores would get the message that customers don't like using those things, but they keep trying to force us to use them. (Lowe's and Home Depot are the same, along with my supermarket chain.)
The Jumbo near where I was staying in Santiago had 74 check-out lanes (numbered, to make it easy for me). On any given day, at least 70 of those lanes were manned and open. Chile doesn't have a minimum wage, so they provide 70 jobs where a Super Wal-Mart provides maybe five.
Interesting comparison.