They see you when you're sleeping. (Or sleepwalking, maybe.) They know when you're awake (and aware of specials). They know if you've been paying attention to the shopper specials. They can tell when you get excited about a price break.
Walmart has been pushing use of RFID tagging for both logistics and inventory management for fifteen years. They started at pallet and case level, and eventually wanted to move to individual item level.See
The lovely and talented Mrs. Fly, on the rare occasion when I actually go to a store and even rarer occasion when it is with her, laughs at me because I'm all over the place when it comes to my path. I'd probably break their code with my erratic pattern.
This means the carts are powered and have intelligence in them. Very expensive. Not sure that is suitable for long term use or storage outdoors and possibly under a bridge deck somewhere.