> IIRC one bank accidently paid off the loan of one of their boderline-default customers to another bank and then couldnt get the money back
That was a story because it was an incredibly unusual set of circumstances that meant they didn't get their money back - the bank owed the recipients money to repay a loan, and as such the money sent could easily have been a prepayment of the loan, which often happens before legal action is started, as happened a couple of days later. There was no way to distinguish an intentional action and a mistake here, hence the court ruling in favour of the recipient.
That was a story because it was an incredibly unusual set of circumstances that meant they didn't get their money back - the bank owed the recipients money to repay a loan, and as such the money sent could easily have been a prepayment of the loan, which often happens before legal action is started, as happened a couple of days later. There was no way to distinguish an intentional action and a mistake here, hence the court ruling in favour of the recipient.