1977 to 1980, there were only 3 National tv stations, 3 local/city-run tv stations and maybe 3 Tv stations from neighboring cities, depending on how big your city and how good your non-antenna cable service.
There were NO Vhs, Dvd, superstations, specialty stations and Internet to air and help fund Tv shows.
And Comics at that time was a FRING, Obscure Pop-culture entertainment. No one would invest or fund money to make a Superman movie, until Marlon Brando signed on. Plus 1978 was just 4-6 years into Warner Brothers ownership of DC comics.
How did Tv stations and the Powers-that-be greenlit Tv stations, ...they followed trends, some Marketing research and entertainment news. With Supes going to the theaters, maybe there will be buzz for Superhero-led crime fighting tv shows.
1978 was also the phasing out of Police Crime fighters, like McMillian and wife, Starsky and Hutch, Columbo, McCloud, etc, and the emerging of Private Detectives like Rockford files, ...which led to Magnum PI, Remington Steel, etc, in the 80s. So, Superheroes were like the Private citizens investigating crimes and doing something.
Since Tv stations relying on Advertisements to sponsor the Tv show and local Tv stations to buy the show to air it in their district, they looked for what they can make quickly, nearby with their resources (Like in California and their pools of actors), and above all cheaply.
So, Car and helicopter chases were easy to shoot and provided great action scenes. Only fight scenes were difficult to shoot. They had to conform to the violence codes and standards, plus people moved too fast for the camera to pick up. Many of the Bruce Lee fight scenes in the Green Hornet show were cut out because nobody can see what's going on.
CBS and Universal were to make 6 Marvel characters for Tv. The Incredible Hulk got 5 seasons (Over 100 episodes). Spider man was difficult to make, the swinging, climbing on walls, trying to make LA into NY, etc, but it got 3 Tv movies and 11 episodes, Captain America got 2 Tv movies and Dr. Strange just got 1 movie.
After 1979, CBS bought Wonder Woman from ABC ran that for 2 seasons, shut down Spidey, and ran the Hulk until new management shut that down.
Captain America was suppose to be a Mid-season replacement, but that was nixed with New Management ending Marvel/Universal deal.
My research came from Comic scene magazine and Stan's soapbox, when he was promoting the Captain America tv show.
For 5 years in the 80s, a local Tv station aired the 2 Captain America movies on Christmas and New Years' night. One of my fondest memories and tv viewing times of my childhood.