Because it's not going to negativity impact the life of any of the people who orchestrated that fraud, and considering bankers made dynastic amount of money pulling such shit, they really have no incentive to stop that behavior.The article you're quoting puts the fines in the billions of dollars and says they're all record-setting. "Slap on the wrist."
Get filthy rich doing whatever you fucking want, and if you get caught, shareholders are going to see slightly smaller profits for a quarter.
Damn it feel good to be a bankster.