Really the big difference between it and an opera is the words. One of the reasons is because they don't think they'll be able to understand the plot. They don't understand what's taking place. Now we go from scene to scene, and no one is lost. People even laugh at the right time in our comedies.
Supertitles are the words of the text projected just above the stage.
You sit back, listen, and watch the show. And with just a glance, you can read exactly what's being said. It's like watching a movie with subtitles. Then, all of a sudden, it gripped me. I didn't even know I was reading the subtitles.