100% correct. It is like going to the grocery store or any big box store with regards to how people dress and the service expected and given.
About 35+ years ago when USAir had a hub in Dayton a small group of us flew first class and non-stop to San Francisco. Jacket with a nice shirt and slacks for the men and a dress or comparable for the ladies. Champaign, drinks and filet mignon served on real china! BTW, the first class upgrade was free (case of beer) as I had a friend who was an agent at the time. My how things have changed!