According to “the trade association for the world's airlines, representing over 290 airlines or 83% of total scheduled traffic.” Which, of course, would like VERY much for you to believe that deregulation was/is a good thing"Since passenger deregulation in 1978, airline prices have fallen 44.9 percent in real terms according to the Air Transport Association."
Source: https://www.econlib.org/library/Enc/AirlineDeregulation.html
A more critical and overarching assessment reads:
“Deregulation also led to poor services and many customer complaints. In 1978, all tickets were refundable, you could change flights with no penalties, travelers would be compensated for canceled flights, seats had more leg room, meals were free, and checking bags was free.
By 2007, the airlines had enough monopoly power to charge for checked bags, charge up to $200 for a ticket change, eliminate food, reduce leg room, abandon routes to smaller cities, and, of course, raise airfares.
Airlines' non-ticket revenue increased to $15 billion a year.”
In other words, please look at these specific lower ticket prices and not the higher ones PLUS all these new fees this far smaller pool of airline companies (as so many went under) are using to obtain more money from you.