Uh, you stated the answer yourself. Corporations are accountable to their shareholders. They maximize profit, that is the only thing they do, and that is in fact a legal obligation that public company boards can be sued for breaching. You call them "publicly-owned" corporations but that is incorrect, they are in fact PRIVATELY OWNED.

The government including regulatory agencies like the FCC have a responsibility to take public interest into account - yes it is never done perfectly - but the FACT is that the decision-making process for governmental entities is entirely different than it is for private corporations.