I've worked in banking. I (re)wrote a fuel estimation program for cargo aircraft (so software that is used only prior to a flight). Let's just say the two have very little to do with each other when it comes to process and leave it at that.
It could be, and in some cases (for instance the transaction portion, interest calculations) it should be. Reporting and statistics are less important and an error there could be fixed without affecting the balances, especially when it is internal stuff.
