Final answer:
Private carriers are companies that transport their own freight and goods and would prefer a narrow market definition, like 'the market for intercity bus service', to minimize perceived competition for regulatory purposes, as seen in the past deregulation of transportation under President Carter.
Step-by-step explanation:
Private carriers are companies that transport goods or freight, typically for their own business needs, rather than for other companies or the public. An example of this can be seen in global trade, where cargo ships are used for shipping goods across the world, contributing to the global economy. When it comes to definitions of market areas, like in the case of Greyhound Lines, Inc. and Trailways Transportation System, private carriers typically prefer the narrowest definition, which would be 'the market for intercity bus service' in this context. They choose this definition because it downplays the competition they would face against other modes of transportation, such as personal cars, car rentals, passenger trains, and commuter air flights. This narrower market definition would support their case for merger by suggesting less competition within that specific market.
Deregulation in the transportation sector during President Jimmy Carter's administration allowed companies to compete more freely, including choosing their own routes and setting rates, which has had profound impacts on private carriers and the overall transportation industry.