There is no difference from the customer perspective so the store failed for reasons that have nothing to do with the "just walk out" technology or lack thereof. Why spend lots of money doing R&D only to find out that the concept doesn't sell? Wait for the product to be successful before spending the money to scale it up. Same as anything else.
"Do things that don't scale."
I think the idea could work well but the execution in the field was consistently very poor. There were a few of these at airports with just an intimidating gate and generally non-engaging human standing there.
It was as if they expected everyone to know what to do, but when I’d watch 99% of people just sort of looked at the store, saw the odd gate things, and then just shrugged and walked off. The stores were almost always completely empty amidst a busy concourse.
Even if the tech worked (reports say it didn’t work well) they completely missed the boat on creating a clear customer experience that navigated the new tech.