Public service (or utility) companies may operate under certificates of public convenience and necessity which may limit competition. Their services may be subject to rate control and other regulations which are not common to general businesses.
The concept of public service companies was that, in order to attract sufficient private investment capital and guarantee sufficient revenues to ensure appropriate operations and services, protection from ruinous competition and additional governmental oversight of rates and services were required to balance the needs of the owners of the business with those of the general public.
In the United States, at an interstate level, most airlines, railroad, and trucking and bus transportation services were deregulated in the last quarter of the 20th century. Many of the changes in the laws at the federal level had the effect of deregulation or substantially weakened similar state and local laws regarding the same services.