The scale of record keeping in a place like JP Morgan is enormous. Just payments transactions are about $10 trillion a day. Unless documents are ring fenced from the start and not many systems and people have access to it, it is highly unlikely that someone is able to destroy it in all the right places without anybody noticing.

If you read the link in my previous comment, you'll see this isn't the first time they got fined for bad record keeping practices. In that instance, $125m.