Question about the four exceptions to the governing classification

In The State of Georgia, why is it good for large companies to have the four exceptions (the Standard Exception classifications, the Interchange of Labor rules, the General Exclusion classes, and the Multiple Enterprise rule) to the governing classification and single enterprise rule? Wouldn’t it be cheaper for them to not have them? I understand with the interchange of labor rule in effect, the employer is charged based on the employee’s actual exposure to injury, which saves on the premium but I’m not clear on the other three.

Any explanations would be greatly appreciated.