When Amazon first launched its “Just Walk Out” cashierless checkout solution in 2018, analysts say it had the potential to revolutionize retail. But in April, Amazon pulled the tech from Whole Foods and its U.S. line of Fresh grocery stores. Instead, Amazon focused on selling it to outsiders and installed it in 200 third-party stores in NFL stadiums, arenas, colleges, airports and more. CNBC got the first on-camera tour of the lab used to develop the tech and its new “multi-modal” AI system.