The difference is that Costco pays their employees well enough to keep them around (notice that Costco prints the start year on each employee badge- average retail length of service is 1 year, Costco keeps people around for decades) and so they can learn to use this older software and master it. Most retail operations optimize their inventory management for new people, because they don't expect someone to stick around long enough to master it.
My wife worked at a small regional chain of pharmacies that had an ancient MS-DOS based EHR system. And she mastered that system to the point where people would call her when she was home with me and ask her how to do something, and she would walk them through "okay, hit tab three times then shift-F12 then enter the frabble and then alt-F3 to go to the next screen and enter the drabble." It was difficult to learn it, but if you mastered it you could do everything you needed to do from just muscle memory while you were on the phone arguing with the doctor's office that their prescription was not correct and needed to be changed.
Then the small chain got bought by a national player and their brand new GUI system was brought in. It was a lot easier to learn- discoverability was a lot higher with menus and drop-downs and all of that. But if you stuck around to master it, you could never be as fast as you could with the older system. And that emphasis on quickly integrating new employees- but lower payoff for experience in employees- was clear in every choice that national chain made. They wanted their employees to be completely interchangeable, which meant that they didn't care if you had six months of experience or four years of experience or three decades of experience.
Somehow I think I failed to think very deeply about this very important link! The twin happenings of the elimination of any retail career that pays a living wage, and the availability of GUIs and especially touch-screen GUIs happened simultaneously over a couple of decades, and the touch-screen dummy interface naturally won out. Not just because training that used to take two days for the 'green-screen' system I learned in 2001 now takes 15 minutes of instruction (and even that training is rather redundant for anyone over 95 IQ) -- also because the massive differential in productivity of an expert vs. new cashier/teller/pharmacy tech/etc. only even manifests if people are on the job long enough to become expert. And they're really not anymore.
Kinda why I prefer self-checkout. Even though the UI is firmly in "dummy" territory and I have to use a touch screen, I've used the current iteration of the self-checkout software more transactions than most cashiers I meet at Target, since they seem to have been there about 2 weeks on average.
The GUI also has lag - especially in the era of web-technologies-bloat, more lag than ever - but whether touchscreen or mouse there can't be a buffer, so each lag requires you to stare waiting for the next UI to be drawn.
For me, it's typically a balance between speed and efficency of data to help you make decisions quickly, but should be able to be used by anyone with technical experience.
So less of both. Less 'pretty UI' and less "omfg here is every piece of information shoved together and you need to be a wizard to understand it"