First, I think it is important to acknowledge that the United States does not actually operate entirely as a free market system, as the government does have some regulations in place for different industries, including banks and the automotive industry. These regulations are intended to protect consumers, employees of these industries, the environment, or some combination thereof.
The ways someone might benefit from (relatively) free markets are largely a result of competition. In free markets, companies compete against one another for customers, which forces them to innovate continuously to try to woo consumers. This innovation can lead to increasingly improved products. International companies also get to compete in free markets, which can expose consumers to products made in other countries, which may have different features, be cheaper than domestic products, or both. Competition can also drive down the prices of these products, as companies want consumers to think their product is the best deal so it will be chosen over another company's. This can save consumers money.