"dennis@home" wrote in message
...
On 02/03/2018 20:56, NY wrote:

So are you saying that the scales only look for an increase in weight
(and don't care about the size of the increase) to denote that an item
(not necessarily the one whose bar code has just been scanned) has been
placed in the bag?

yes.
Can you imagine the error rate of thousands of products and just how
difficult it would be. Even the humidity in the shop would affect the
weight of the boxes.
How about the tub of ice cream I bought yesterday that had half an inch of
frost on it that would weight tens of grams more than it should.

Well I've learned something. Ever since the system was introduced, I've
thought that the system knew the weight of every item and checked that the
scales increased by that weight after it had been scanned and was placed in
the bagging area. I'm sure I'm not along in thinking that. I'd not realised
that it was less complicated than that and only looked for *any* increase,
not necessarily of the expected size.

As a matter of interest, do you know this for a fact (eg, having worked on
the development of the system) or are you presuming it from logic (which I
have to say I agree with, now you mention it)?

The biggest problem with the self-scan checkouts is those damn scales. They
expect you to put all your bags on the scale at the outset and to place
things once and forever in a given bag. I find I move things around as I
realise that I'm about to put fresh meat in with cooked meat (a no-no,
according to SWMBO, *even if it's pre-packed and sealed*), or about to put
something heavy on top of something squashable like bread. The system
doesn't like you to temporarily reduce the weight, as you move a completed
bag from one side of the scales to the other, or to move an item between
bags. And I tend to want to scan several small objects at the same time and
then move them all, as a single "item" into a bag - you can't do that,
because the systems expects you scan scan one items, bag it, scan the next,
bag it - in strict order.

Some have better logic than others for items that need approval (eg
alcohol). Some flash the "help needed" light but allow you to carry on
scanning and bagging, whereas others stop dead in their tracks and won't
allow you to do any more until the assistant has verified that this
fifty-odd-year-old man really *is* over 18. Morrisons' logic with this is
good, but one of the other supermarkets' tills (I forget which) are really
fussy. At Morrisons I tend to scan the alcohol as the very first thing so as
to allow as much time as possible for the assistant to arrive before the
drop-dead time of not being able to pay until the assistant has verified.