It definitely wasn't the case with Back to the Future as I know the parties involved with it and everyone (me included) was very surprised that the LoC was not

It definitely wasn't the case with Back to the Future as I know the parties involved with it and everyone (me included) was very surprised that the LoC was not proactive in obtaining and preserving a print of the movie. We assumed that was a mandatory part of the process. It was sad, because I thought of the LoC as the best place to preserve media like this, as I assume they probably attract some of the world's best archivists.