Up to the early 1980s many wore suits and sport coats when traveling in in domestic first. International business and first attire declined through the 1990s. Most dressed on Concorde. The domestic and international business and first service also declined. I can remember being served lobster, filet mignon, duck and shrimp on a regular basis in domestic first. International business service today does not compare to domestic first of the past, other than seat size. First class and busines cabin attire today is about the same 1970's Greyhound Bus attire in the US. Qantas international first class passengers seem better dressed than us in the US.