As someone who has worked a lot of retail, they’re saving 8-16 man hours a day MAX. The national average hourly wage for a cashier is $13.81, so that’s $110.48-220.96. You still need to maintain manned registers so you have bodies for closing duties and a pod of self checkout registers still requires at least 1 body to run them. During non-peak hours it’s perfectly reasonable to only have 1 register open with a pod of SCO’s, and that register is mostly so you can sell alcohol and cigarettes. For closing you still need 3 or 4 bodies to deal with the after work rush and closing duties like trash, counting tills and other miscellaneous duties.

Self checkout only is a tool to improve the productivity of 1 person, some people are just upset at how effective they are, as shown by their prevalence. The real reason to be pissed off is that they don’t care, you’re still going to buy the same amount of stuff, you probably won’t even make any changes to your purchasing habits. This is underscored by the trend of retailers locking more and more inventory behind cages and lockboxes, and sales don’t go down, some retailers even think they result in more sales because more product is available to be purchased.

P.S. As someone speaking from the employees point of view, the biggest issue comes from the fact that consumers want to shop on the weekend to comply with their mon-fri lifestyle. Which in turn means someone else has to give up their “weekend”. This alone accounts for most of the issues I’ve seen post covid with staffing shortages, nobody wants to work when their friends or family aren’t, and they’re not getting any incentive pay for working the crappy hours. As a society at some point we have to recognize that this absurd obsession with weekends leads to most of the frustrations we’re talking about. If people could more evenly distribute their alotted time to do chores we wouldn’t have these gigantic lines to services that nobody wants to work at.