Otherwise as thought experiment, imagine just a tiny 1 Inch tall person glued to the grocery trolley and another sitting on each shelf - just these two alone are all you need for "automated checkout".
I don’t think this would actually work, as silly a thought experiment as it is.
The problem isn’t the vision, it’s state management and cost. It was very easy (but expensive) to see and classify via CV if a person picked something up, it just requires hundreds of concurrent high resolution streams and a way to stitch the global state from all the videos.
A little 1 inch person on each shelf needs a good way to communicate to every other tiny person what they say, and come to consensus. If 5 people/cameras detect person A picking something up, you need to differentiate between every permutation within 5 discrete actions and 1 seen 5 times.
In case you didn’t know, Amazon actually hired hundreds of people in India to review the footage and correct mistakes (for training the models). They literally had a human on each shelf. And they still had issues with the state management. With people.
Distributed communication and state management on the other hand is a solved problem already mostly with known parameters. How else do you think thousand and thousands of Kubernetes work in the wild.
This is important. The autonomous driving problem and the grocery store problem are both about trade-offs, one isn't clearly better than the other.