I think you're confusing modern American liberalism with classical liberalism. Despite the word "liberal", they are pretty different. The emphasis on positive rights, like the right to healthcare, is one of the major distinctions.
Actually I'm purposely mixing them. Liberalism was never as black and white as people made it out to be. Sure John Locke had a long list of reasons why natural rights should be a modern tenant of a just society, but to the average citizen the shift from classical liberalism to contemporary liberalism was a series of steps, each of which made sense.
I understand what you're saying, but the average citizen wasn't alive for both John Locke and the Great Society. I guess I disagree with there even being a shift at all. They are quite different worldviews that unfortunately share the word "liberalism".
http://en.wikipedia.org/wiki/Modern_liberalism_in_the_United...
http://en.wikipedia.org/wiki/Classical_liberalism