> > Which would fail since the cart would detect the RFID tag 
> of the first 
> > item, note it's weight, and then determine the actual increase in 
> > weight doesn't match.
> 
> First, not when 1 item is a 20 pound bag of flour and the 
> other is a 2 ounce memory stick.  Second, now you're talking 
> about a scale in every shopping cart along with the computing 
> infrastructure to support it and probably and RF link.  How 
> much are stores going to pay for shopping carts, especially 
> when carts are stolen all the time.


You weigh the entire cart at checkout.  Don't forget to take the baby out.

You can put an RFID reader in the cart.  There was a trial where this was
done with bar codes, you scanned the products as you added them, and it
displayed the total cost.  A true nerd would have added weight, volume and
density.  In the real world no-one cared.

Or course, getting accurate weights is still a problem as you point out.

tony

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