Corporations are still subject to law and ultimately under the control of the government. The current set of rules just gives them a fair amount of freedom to operate.
This only makes sense in a spherical-cow-in-vacuum world where government and business are somehow barred from communicating with one another. In reality, the "current set of rules" in many countries is a result of companies relentlessly trying to and succeeding in finding ways of influencing government. Political advertisements, campaign funding, lobbying, corruption, underhanded favoritism, countless other methods that are an amazing RoI for any business large enough to engage in it. Large enough corporations are resembling governments more and more in terms of value and power, and they use all of that power to endlessly try to bend the rest of society into serving their profit motive.