I’ve come to appreciate, though not love, those manual checkout
lanes in the grocery store. If they haven’t come to your town,
they allow shoppers to ring up and pay for their own purchases,
without having a cashier do it. At my local Jewel/Osco, four manual
lanes take up the space of two lanes that used to be staffed by a
clerk.


The checkout system is simple. You scan the item, and the price
and description show up on the screen, and you bag the item in one
of the three plastic bag holders to the right of the scanner. The
bag holders, and the shelf on which they rest, are on a big scale
that keeps track of the weight of your purchases. If you “forget”
to scan an item and bag it, it tells you “hey, you put an item in
a bag without scanning it.” (Actually, the female computerized
voice is much nicer about it.) If you take something off the shelf,
or put a bag back in your cart, you have to click a little “item(s)
removed” button so the scale recalibrates. The scanner is about
three feet off the ground, and the scale/shelf is two feet high.


The system works well enough. After a few items, and you get used
to the quirks of the rhythm of scan-bag-scan-bag-scan-bag, it’s
pretty quick. Some people hate it, but I think it’s more from fear
of the new, rather than it being very difficult.


However, I believe I found a scenario that the designers didn’t
take into account: Ringing up your groceries with a four-year-old
in tow.


On Sunday, Quinn and I
selected about 40 items and went to the manual checkout lane. I
started checking out items, and Quinn wanted to help, of course.
She grabbed a can of Spaghetti-O’s out of the cart, and put it up
on the scanner (”boop!”), right as I had scanned a box of Triscuits
(”boop!”). The register was not happy at having the Spaghetti-O’s
scanned before I’d bagged the Triscuits, so up pops an error. I
had to wait for the system to get itself back in sync before I could
continue, but Quinn went to get a can of alphabet chicken soup and
tried to scan that, which only made things worse.


After a few attempts at this, I implored Quinn to let Daddy do the
groceries. “Please just wait a minute, honey, and we’ll go out to
the car, OK?” She wasn’t too happy about it, but she was a good
girl and decided to sit quietly… on the shelf.


Suffice to say the system didn’t account for an unscanned four-year-old.
I had to explain that she couldn’t sit on the shelf with the bags,
so she stood next to it… for about 15 seconds before she put her
hand on the shelf and leaned on it.


Human cashiers still win as far as fault tolerance.

What other systems have fallen afoul of a four-year-old?