We have to love the curtain divider! Although if you are sat in the front of Euro Traveller, crew and passengers passing through it need to be careful. I have witnessed several near misses with people charging through the curtain only to find someone or something immediately on the other side. Recently that included a passenger holding his child while the window seat passenger tried to get out and suddenly a trolley was energetically being pushed through the curtain. Some airlines actually use transparent fabric for health and safety reasons.
But many of us might remember the days where on BA longhaul 747s, up until the early 2000s or so, a red rope was placed across the cabin zones and signs such as “First Class/ Club World passengers only beyond this point” were the norm.