Because if they are, then I think we may have to disagree on what constitutes a "serious consequence", as per the original posters point.
And if we don't know that, then we're not really in a position to know if there have been sufficiently serious consequences for those involved.
Hell, I'll pay the 15 billion dollar fine if I can do it with Volkswagen money and you don't touch my assets, the money I took out of the company as salary while doing the crime, or jail me.
Serious consequences laid on a corporation don't do anything, because there's no conscious being there to react to, perceive, or experience those negative consequences. They especially don't do anything if you're managing other people's money and the executive class receives relatively little personal punishment.