I watched the first half of the The Good, Bad, Weird last night, and I immediately could tell that it was recorded in 1080i.  (Easiest for me to tell with larger scale outdoor pans, and that's how the movie opens IIRC.)  So I see that this is simply how the US bluray is recorded, wtheck.  I think foreign versions get the progressive?  

  That said, for being interlaced, it's as good as it comes.  I bet that if it was given as 1080p, it would look really really top notch.