To answer your rhetorical question, America is coming from being a hyper free market system, in which both culturally and legally people were expected to fend for themselves. This approach was extremely ingrained into American life for 200 years. Culturally the attitude was all-pervasive, and it was regarded as something that made Americans distinctive: self-reliance.
Given America is by far the world's largest economy, and possesses a fairly complex sociocultural system (significant diversity in most every respect, many competing large interests), I'm not sure why anybody would think transitioning to a soft-Socialism or "modern welfare state" model would be fast or easy.
Given America is by far the world's largest economy, and possesses a fairly complex sociocultural system (significant diversity in most every respect, many competing large interests), I'm not sure why anybody would think transitioning to a soft-Socialism or "modern welfare state" model would be fast or easy.