I wasn't suggesting that this shouldn't have happened, or that it isn't a massive screw up, rather that banking systems are far more complex than generally given credit for.
Consider: A production server fails, you fail over to the DR server with it's copy of the disk in a remote site. Easy, probably even automated.
However: A database corruption occurs, this corruption would have been instantly transfered to the DR disk, so that DR server is totally useless. You (probaby) have snapshots from Start of day, or end of previous day (pre-batch). Did the batch corrupt the database? Do you want to recover from pre-batch, or post batch? If the batch corrupted the database, how? Do you need to re-run the batch, can it be re-run the next night? How long does it take to run? Did another server cause the corruption, at a guess a dialin system like merchant handsets would be using a bigass unix box, or Tandem, almost certainly talking to a back end mainframe, probably via some sort of broker... etc. etc. etc.
This is just one of many scenarios that could have happened, rather simplified one as well, but illustrates how DR can be rendered pretty useless. It doesn't even consider the reuqirement to recover from tape.