Please don't get into the technicalities. Monopolies do exist. Producing something that has a small market for it is still a monopoly, no less. I can think of the concession stands at the movie theaters, as a case in point. However, the federal government is not interested in enforcing antitrust laws on those concession stands. I'm not very familiar with antitrust laws, but I think this is because the monopoly that concession stands have doesn't have such a significant impact on the aggregate economy.
- Celine