Almost no one arrives late at the Met. If you're not there at Post Time, they don't let you in until intermission or a scenery change break.
ML/NJ
Houston was like that, too. I was with a friend who has Chronic Lateness, and we had to watch the first act of “Turandot” on a monitor in the lobby.
However, during Wagner’s lifetime, the Parisian upper crust would arrive at the opera late - or so my dear old professor said, and he was nearly old enough to have been there!