1) Upper management are morons that have no idea what is going on in their company. It's the equivalent of a farmer claiming he had no idea that his 'organic' corn is actually bio-engineered and covered with Round-Up.
2) That they personally are directly and legally responsible by failing to manage their employees. The buck stops at the BOSS, not the janitor.
3) Are also committing the Wage-Theft by not doing their official declared job of MANAGING their employees.
Claiming ignorance, stupidity, and incompetence is not a valid legal defense.