This is quite unsurprising, since the political system in the United States is very authoritarian. The entire political discourse lies between the authoritaria

This is quite unsurprising, since the political system in the United States is very authoritarian. The entire political discourse lies between the authoritarian center (Democrats) or the authoritarian far right (Republican). There are no real libertarians. There were a few fringe candidates in the past (e.g. Ralph Nader, Ron Paul) who were basically unelectable, and there are a few fringe candidates now (e.g. Rand Paul) who have begun singing the tune of authoritarian government to get elected.