A lot of it from what I can tell is American exceptionalism. That we are special and unique and therefore what goes on in the rest of the world simply does not matter.

Often this is rephrased as the U.S. is too big or too diverse compared to European countries. Or it can be a simple ignoring of any alternatives or an active movement against. I remember hearing an NPR article about how a US construction worker wanted to go and study the methods of infrastructure improvements in Europe which tended to be cheaper in the same realm, but was denied. The reason for denial was something along the lines as it wasn't pertinent, we didn't need to know that.