I've noticed the lines outside flagship luxury stores and boutiques (even Longchamp inside Galleries LaFayette in Paris) ever since my childhood, and now I'm 51 years old.
About six years ago I toured the LV museum, while there I asked about the lack of clientele inside luxury boutiques while the line outside is a block long. I was told it comes down to two things- shoplifting/snatch and run issues, and too many clients being shown products lessens the ability for the SA's to show their client items. They can't show you two or three bags when other SA's have those bags out showing their clients. Then when other SA's are finished, who gets to see the bags next, if many SA's have been waiting?
I hope they go to online appointments booking. Imho, the lines look tacky and people abuse them by having one person hold spaces for several people interested in purchasing. Yes, I am that person who has waited dutifully in line, has had a woman in front of me invite five young and able bodied people/families, who were maybe on the same tour, to stand with her after they strike up a conversation outside the ropes.
I haven't waiting in a line for at least 20 years. I don't have the patience or the want of a bag (that much).
If the queues must continue, a hand stamp or something should happen.