Laymen here: my guess would be that the financial and social resources corporate representatives have access to (both personally and through the entity that has a vested interest in them not going to jail) make the prospect of prosecuting them for criminal misconduct unappetizing. It would be a lot of time and money to send people with a lot of powerful friends to jail for a handful of years, at best. As a prosecutor, what's better for your career: that, or spending significantly fewer resources putting street-level criminals in prison for 5, 10, 20 years?

The issues at hand seem distinct but related.