What a joke. This is not only some big brother bs being portrayed as "enhancing the customer experience".... its frickin comical in that they claim they are going to send someone to the register to ask a customer why they're upset. If they'd actually use these mystery employees to open more registers and/or actually staff the various departments with floor people... they wouldn't have to do this. They need to just drop the bs and just call it what it really is...the next generation of risk management. And they could probably buy the software off the shelf already. Casino's have been using it for years to spot cheats. http://www.businessinsider.com/walmart-is-developing-a-robot-that-identifies-unhappy-shoppers-2017-7
The question "Why are you upset?" is a bit invasive, in my opinion. Clients might have personal reasons to be upset which could have nothing to do with their shopping experience, and those reasons aren't anyone's business but their own, after all.