It's a two party situation if both parties are aware of it. I didn't read any implication in the article that the bank knew about this, it was a mistake either

It's a two party situation if both parties are aware of it. I didn't read any implication in the article that the bank knew about this, it was a mistake either human or software that led to him having the credit line. so only one party was aware of it, the customer, therefore their responsibility for the borrowing.