Pretty sure that middle class Americans rarely flew before deregulation in the late 70s. My mom's middle class parents packed the kids up in the car and took a few epic road trips to visit family in other parts of the country in the 60s - flying would have been unimaginable.
Flying was definitely better back before de-regulation. Google Pan American and look at how big the seats were and the food served. Much better, but roughly 4x the price (comparing LAX to Heathrow).
The upper middle class were the ones well-off enough to have flown in the 60s/70s but still price-sensitive enough to penny-pinch themselves into misery after deregulation.
