Although the functions of a regulatory commission are fairly straightforward in theory, in practice its task is far more complex and, in some respects, impossible. Moreover, the political climate in which regulatory commissions operate often leads to policies and results directly the opposite of what was expected by those who created such commissions.
Ideally, a regulatory commission would set prices where they would have been if there were a competitive marketplace. In practice, there is no way to know what those prices would be. Only the actual functioning of a market itself could reveal such prices, with the less efficient firms being eliminated by bankruptcy and only the most efficient surviving, with their lower prices now being the market prices. No outside observers can know what the most efficient ways of operating a given firm or industry are. Indeed, many managements within an industry discover the hard way that what they thought was the most efficient way to do things was not efficient enough to meet the competition, and end up losing customers as a result. The most that a regulatory agency can do is accept what appear to be reasonable production costs and allow the monopoly to make what seems to be a reasonable profit over and above such costs.
Thomas Sowell, Basic Economics (2010), Ch. 7. Big Business and Government