Airlines were heavily regulated in the US and essentially operated as government contractors until 1978 [1]
As I understand it, everything about the industry was better back then too.
Case in point: Old Perry Mason shows where characters regularly drive to the airport, pay for a ticket and get on a plane. Flying was actually faster than driving back then, even when measured by time between deciding to leave and arriving at destination!
(Yes, tickets used to cost a bit more. Whatever. Figure in the price for camping in the airport for 4-5 hours, and then tell me the current system is cheaper!)
Was it cheaper or more expensive for the public to fly on them during that time or after deregulation?
Yeah and it was an absurdly expensive activity limited to rich people