Final answer:
The U.S. has a mixed economy with capitalist elements and government intervention through regulation and public service provision, which does not negate its capitalist character but demonstrates a blend of systems.
Step-by-step explanation:
The presence of publicly funded services such as mass transit and the delivery of 1st-class mail by the federal government does not negate the overall capitalist nature of the United States economy. Instead, it illustrates that the United States has a mixed economy, combining elements of capitalism and government intervention. The government regulates businesses through laws and regulations, provides certain public services, intervenes in times of economic crisis, and operates public utilities and services, which all indicate a blend of economic systems rather than a pure capitalist economy.