Curtains seem pointless on U.S. carriers. They are see through and half the time left open. There is like respect for a premium product in the U.S. I flew Qatar and Turkish and they didn't even open the curtains for coach until the other classes had deplaned. The U.S. used to be like this. I remember deplaning on United and coming down the spiral staircase on a United 747 and they would not allow business to deplane until First had exited.