I started using grocery self-checkouts during COVID, but I've kept using them because there's rarely a line (and I'm a misanthrope). I'd probably go back to using regular human checkouts if I had to dig through all my crap to prove what I bought.
Having said that, I've noticed myself making mistakes. I've accidentally failed to scan an item, and I've accidentally entered incorrect codes for produce. When I notice, I fix them, but I've probably missed a few.
I guess the easiest answer is for grocery chains to reinvest some of those windfall profits and hire more cashiers.
I don't use self-checkouts in retail stores, and I hate that some stores, like Shoppers, will try so hard to direct me to one when I'm in the queue for the cashier. I have put down merch and walked out of stores over this stance, and I no longer visit some stores (like Shoppers).
I'm not entirely against automated purchase systems. A completely touchless system would get a pass from me. I am against retailers forcing their customers to manually scan and check-out their products though, all while treating them as untrustworthy by dictating where they can place their scanned merch, weighing the merch as it's scanned, and checking the receipts after doing so.
Obviously, none of this addresses the question of whether fully-automated retail spaces are actually good for the working class as a whole.
My local No Frills has shut down their express lane and directs people to their newly built self checkout. It's basically the express lane except instead of the cashier scanning my items and taking the payment. I scan the items and give payment while a cashier hovers over my shoulder to make sure I'm not stealing anything