"The account" is the amount of money that the bank attributes to you when it is drawn upon. Yes. And the scenario I propose is that your bank statement says

"The account" is the amount of money that the bank attributes to you when it is drawn upon. Yes. And the scenario I propose is that your bank statement says you withdrew an amount and later regained that amount, while in the intermediate time the actual amount attributed to you by the bank was always the original amount. If a significant other was withdrawing from the same account at the same time, it may have been possible to overdraw beyond the usual limit. As long as that would eventually come to light, due to eventual consistency, that's not a problem (and undoubtedly something you contractually agreed to take as a risk). Transactional algorithms usually require logging to be able to recover from failures. A conclusion of the recovery process can be that certain actions did not take place. A bank statement is a rather sparse log that underspecifies what actually happened.