Zhang Dawei wrote:
They wait until the item is on the scales before they allow the
next one to be scanned. It can be a real pain.

Agreed. It caught me out the first time I used one these things: what
I was all set up for doing was to quickly scan the items, then place
them immediately into the shopping trolley I had brought to carry the
stuff home on the bus. In the end, it took me much longer to take the
stuff out of the supermarket trolley, scan it, place on the
(smallish) area which turned out to be the weighing area, and then to
take it all off that again at the end to place it into my own
shopping trolley. What a waste of time and a hold-up!

I wholly agree. I've tried to use them at Tesco (various stores) and B & Q,
(one store) and have failed every time.Last week at a Tesco in wild west
North Wales, I tried to barcode through two packs of batteries that I don't
think are security sensitive. It would not allow me to register more than
one.

Fortunately, I saw a checkout counter with a human becoming free and went
through without a hitch.

A Tesco droid was having fun trying to reset the machine as I left!