Federal authorities have arrested a top corporate executive accused of defrauding regulators and the public. The FBI on Saturday arrested Oliver Schmidt, a Volkswagen executive in Florida, alleging that he played a central role in conspiring to keep U.S. regulators in the dark that diesel vehicles made by the company were designed and programmed to cheat on emissions tests.

That’s good news. But if federal authorities could find a basis for criminal charges against fraud in car emissions, how come there was not a single arrest or prosecution of any senior Wall Street banker for the systemic fraud behind the 2008 financial crisis? That, too, doesn’t pass the smell test.