Prices were also regulated and fixed by the federal government. The federal government through the Civil Aeronautics Board set ALL domestic flight fares based on a fixed distance calculation.

Airlines literally couldn't compete on price, so they competed on perks.

In 1977, just prior to the Airline Deregulation Act of 1978, the average round trip domestic flight was ~$135. That's about $746 today. Round trip NY to LA was $148.20, or $820 today. Just looking at google flights for the next 6 months, The cheapest I can find pretty consistently for the same route is $239, and the highest I see is around Thanksgiving and Christmas for around $540.

Call it enshittification, call it whatever. Flying is so much more accessible and cheaper than ever. And that has its benefits and drawbacks. The drawback is that people now look at price first and foremost and are generally unwilling to pay more for the perks beyond a little more legroom. The benefit is that it's ridiculously easy to just pack a backpack and go on a weekend trip across the country for dirt cheap.