Management just didn't RTFM/FTFM.
It was based on Windows NT (somehow hardened, as I never saw a checkout show a BSOD or fail to boot) and was designed before a time when you had a continuous internet connection. There was a mini-server in the back office, and every night it would sync with HQ.
This meant all functionality, including taking credit card payments and loyalty, could be done offline. One time we had a electrical systems failure in the store, and everything - including chillers - went down. However each checkout had its own UPS and continued to operate without issue.
But it was against policy to use the feature, since previous cashiers had worked out a way to scam the system somehow and pocket some of the cash being exchanged. I'm cloudy on the exact details after so long, but it was very, very annoying to have such a useful feature sitting there mocking me and a write up if I dared hit the button.
It would be smarter for that feature to require a manager's key, and then the manager could actively monitor the situation. But since the manager can't implement that feature, they have to work with what they have.
Blanket bans like the one described are always wrong. ;)
If there's a problem, monitor it after every shift, or every day, or weekly. You know who worked what registers; monitor/scan/review, then take action against the offenders.
I worked food service with POS; we had to review things every drawer change, and discrepancies were noted. Repeated discrepancies (either money or between food usage and money) would be tied to someone (or multiple people) and action was taken. It's not always that hard, just a bit time consuming, but... it's part of the job (or was for me).
It is also one of the most annoying mistakes I see frequently repeated at startups and young businesses.
Solution: don't hire scummy people, pay enough that you can afford decent folks, watch for a friend that always comes to a certain cashier especially while alone, watch for cashier being nervous when observed, watch for partner to break off transaction if observed, "forget card", or return goods shortly.
It's also obviously trivial to catch with the receipt but they will probably refuse to show it. A transaction log will also trivially show it if matched with register and time.
Anyone could potentially get away with this once but any dishonest person is going to want to do this repeatedly.
There is basically no excuse for not catching this as a manager and I see no reason to deny associates this useful feature.
Management didn't bother checking for unusual rates of suspended transactions nor 'check off' on abandoned transactions.
It's almost always a management failure, as it's most likely they just didn't want to do the work instead of wasting time hitting on the inappropriately young employees...
Closed loop cards are integrated between the POS backend and the program manager. Some large merchants manage their own card programs.
I guess there is fear their purchased goods might be stolen.