We are. At least going back to the first Roosevelt administration. And possibly going back to labor reforms following the Haymarket Square riots in the 1880s. Unregulated capitalism was amoral, predatory, and in some cases lethal.
Technically, when RW-ers say "socialism," they are somewhat misusing the term, which means government ownership of all means of production, as well as services. In the U.S. what we have is democratically regulated capitalism, where the government does not own, but exercises some control over, producers and the commodification of labor.