Comment Re:RFID (Score 1) 161
Inducing the power in the RFID tags of a whole basket full of items causes them all to (very, very rapidly, before they run out of power) transmit their message on the same frequencies as everything around them.
You simply don't have time for them to hold-off and retransmit as they're only induced for a fraction of a second as the field moves past them, and so you don't really have time for retransmission, verification, etc.
With commodity scanners, you just get a load of noise talking over each other, you would need to design a specialist scanner that can repeatedly reactivate them, and for every item to have a unique code (so, unlike a barcode, every individual item would have to be programmed differently) and some way to check that you haven't missed anything in the basket.
It also means literally tagging every product with a unique code before it gets on the shelf. Not just a barcode for the product type, but a per-item, RFID tag containing metal, a unique serial, a unique ID for database lookup, etc. That's really quite simple... but also quite time consuming, labour intensive and expensive however you look at it. I bet even Amazon warehouses don't label every individual product like that, just what product they are / bin they were in / a 2D thermal-printed barcode. It's also the case that no manufacturers I'm aware of label, say, every one of their packets of cornflakes with such a unique RFID code out of the factory.
It's all "possible", but nobody has ever bothered to get that far because of the sheer logistics and expense. Even at a penny per item, deployed by robots, with a backend database with already-absorbed costs, you're looking at SO MUCH work. And then you have to have special scanners in every single store, costing way more than just an ordinary RFID scanner if you want them to be vaguely accurate.
As always, the market dictates what's acceptable and what's not - and it's apparently cheaper to hire thousands of Indians watching dozens of video streams each than it is to bother with the above, and that's in a "pioneer" of that kind of technology in mainstream use.