Laissez-faire economics began losing dominance in the late 1800s as the costs of unregulated industrial capitalism became hard to ignore. Trusts and monopolies squeezed competitors, urban slums spread, financial panics caused severe depressions, and labor movements demanded protection. By the time John Maynard Keynes published the General Theory of Employment, Interest and Money in 1936, the intellectual center of gravity had shifted decisively toward more activist government.

No. The United States has extensive federal, state, and local regulation covering labor, finance, food safety, environment, healthcare, transportation, and many other sectors. Total government spending in the U.S. is roughly a third of GDP. While the U.S. is generally lighter on regulation than some European peers in certain areas, no serious economist describes it as laissez-faire.

No. Capitalism is a system of private ownership of the means of production. Laissez-faire is a policy stance that says governments should interfere with that system as little as possible. You can have capitalism without laissez-faire (the United States, Germany, and Japan all have regulated capitalist economies) and you can theoretically have markets under different ownership structures, though in practice the two usually travel together.