At one of the stores, Lisa found a full case of 18 items of a given thing that she wanted. We went to check out, pointed out that it was a full case of 18. The checker pulled one item out and started waving it across the scanner over and over again, clearly meaning to scan it 18 times.
Lisa got so disgusted at the stupidity of this that she said, "Never mind, we're not buying anything here" and we walked away. She did go back and talk to the manager, who insisted that this was "policy" and that they weren't allowed to do 18@ [scan], for inventory accuracy. Well, that possibly makes a bit of sense, but if that were the case, then the checker should have been scanning each item, just in case one of them wasn't the same as the others. Also, the more you do that multi-scanning, the more likely you are to get the count wrong. The manager said, "Oh, you just have to take the receipt and count the items to make sure."
If Lisa ever decides to give them any more of her business, she will break up the cases and scatter the items randomly to force them to scan each one individually. At least that way we're more likely to get charged for the correct number of items.
So on to the next store, where by coincidence Lisa found another 18 items of a different thing, this time in three sets of 6. We went to the counter and began to check out. When we got to the three 6-packs, Lisa realized that she'd left two items behind. I told the clerk, "Charge me for 18 of these bottles, and Lisa will go get two more." The clerk cheerfully did 18@ and scanned one bottle. I paid for the total (including the other things we got, of course), and Lisa brought two more bottles to put with the others.
On the grounds that compliments are deserved as well, Lisa made a point of asking for the manager and complimented both the checker and the store for having a sensible check-out policy, explaining what had happened to us earlier that day. The manager was horrified at the idea of someone waving the same item 18 times to do this transaction.
I work in inventory management. I spend a significant amount of my day processing inventory errors and tracking down why things aren't matching. I really do understand why a store might disable multi-count scanning. But the way that store A has done so makes inventory errors more likely, not less. It's clearly a case of implementing a policy ("don't do multi-count scans") blindly without thinking through the consequences.