> would see the screen freeze as the user was attempting to confirm receipt of cash. Each time the user pressed “enter” on the frozen screen, it would silently update the record

Consider the shittiest homegrown shopping portal probably doesn't do that and any commercial point of sale system absolutely won't do that either. The system has to be such a POS internally that no other vendor will take the liability for it.

Reminds me of the Therac-25 that killed people. This thing probably killed more people than that.