Is it my imagination or did theaters (a long long time ago) used to start the movie trailers before the movie's scheduled time? That way the movie would start when the theater said it would, rather than fifteen minutes after that time because of commercials and trailers.
I could have sworn this used to be the practice.
It did. Nowadays the movie usually starts about 15-20 minutes after its scheduled time, though I don't mind. It gives the latecomers an extra 15 minutes to show up without distracting from the actual film.