That said, the right is also authoritarian, and to a degree, the left and right are only different on the irrelevant issues... But on truly important matters they always act in bipartisan ways.
Take bush -> obama. It might as well have been like a relay race where bush made it to the end of his run and hands the baton to obama who keeps running on the same track... Except with left cover he's got away with far more than bush could have ever dreamed.