Actually, we wouldn't mind if every movie theater in the world did this for every movie. There's nothing worse than settling down to watch a film, only to have latecomers walk in when the movie has already started and break the atmosphere. 'Saving Private Ryan' is a completely immersive movie that creates a vivid world and draws its viewers in. Keeping that feeling is integral if the film is to have its desired effect on the people watching it.
Spielberg didn't want any of that atmosphere to be lost, so he made every theater showing his movie make a promise; when the movie had started, nobody was to be allowed in. The doors were closed, and if you arrived late it was too bad, and you'd have to wait for the next showing. Keep the volume up, and keep the doors closed. We don't think that should be too much to ask!