Most manufacturing specs in US industries such as aerospace and defense are extremely well defined. They don't usually leave enough meat to cut corners in significant areas. They are typically fairly robust in that they are self-assuring. When specs are written correctly they are extremely difficult to subvert in one area and still come up with anything that could be confused with a conforming product. Plus the penalties for actively subverting these specs can be quite severe.
That said, I can almost guarantee the specs for automotive manufacturers are less strict and the penalties less severe simply because the specs are made to be cost-centric rather than performance-centric.