Re: Pickpockets paradise
I read a review of this tech. Your specific example of filching stuff from another shopper's trolley was not tested but from other tests I would expect the system to charge the correct person unless it is done by the toilets. The reviewer tried picking things up, putting them back, putting stuff away and trying to hide from the cameras. The system handled all of that fine.
There were two classes of failure. The first shoppers are warned about: If you pick something up and leave it on the shelf next to the entrance to the toilets you will be charged for it. The trick that worked was to sign in, pick stuff up, go to the toilets, get changed, come out, pick up more stuff and leave. Eventually you will be charged for the first set of purchases but not for the second. Amazon have been made aware of this cheat and perhaps they are dealing with it.
Something else that was not tested in the review is a family shopping trip: What happens when a parent signs in and a child picks stuff up?
The Amazon shops require customers to log in with their smart phones and pay by a credit card linked to an account. This is a problem under US and UK law: shops are required to accept cash. The lack of a cash option is a deal breaker for me. I also require a paper receipt. Hiding stuff up your jumper is not a crime but leaving the shop without paying is. I want the receipt as evidence that I have paid for the correct collection of purchases before I leave.
At least this system is honest about recording you with hundreds of cameras. I have not seen any warnings about the existing system of tracking how your phone moves around the shop using the free WIFI.