The United States has a free enterprise economy because it has a market-based economy. In a market-based economy, prices are determined by supply and demand, rather than by the government. This allows individuals and businesses to make their own economic decisions based on their own self-interest.
There are some regulations on the economy, but these are designed to ensure that the market works fairly and efficiently, rather than to control the economy. The United States also has a mixed economy, which means that some industries are owned and operated by the government, such as the postal service. However, the majority of industries are owned and operated by private individuals and businesses.