The economic complexities involved when regulatory agencies set prices are compounded by political complexities. Regulatory agencies are often set up after some political crusaders have successfully launched investigations or publicity campaigns that convince the authorities to establish a permanent commission to oversee and control a monopoly or some group of firms few enough in number to be a threat to behave in collusion as if they were one monopoly. However, after a commission has been set up and its powers established, crusaders and the media tend to lose interest over the years and turn their attention to other things. Meanwhile, the firms being regulated continue to take a keen interest in the activities of the commission and to lobby the government for favorable regulations and favorable appointments of individuals to these commissions.
The net result of these asymmetrical outside interests on these agencies is that commissions set up to keep a given firm or industry within bounds, for the benefit of the consumers, often metamorphose into agencies seeking to protect the existing regulated firms from threats arising from new firms with new technology or new organizational methods.
Thomas Sowell, Basic Economics (2010), Ch. 7. Big Business and Government