There's a lot of competeing "cable was started" stories
Basic cable was never ad free.
Premium cable channels came later. to quote a post up stream "Sound familiar?"
But cable channels were ad free, and advertised as being ad free.
"Well, Pay TV is fine to see
You get much better quality:
Broadway shows, heavy-weight fights
First-run movies every night.
Viewers of Denver, unite! . . . Nothing to lose but commercials."
-- Talkin' Pay TV by Phil Ochs, 1963
Premium channels like HBO always cost extra and were ad free and still are on cable.
According to most articles I see, for the first 24 years after commercial cable TV was a thing, it was solely used to retransmit broadcast TV.
https://web.archive.org/web/20100905133543/http://www.ncta.c...
Basic cable has never been ad free. Cable started out as a method to get broadcast TV - with ads - to people who couldn’t get it over the air.
Then the “Superstations” came like TBS and WGN. They were local stations - with ads - that got transmitted nationwide.
Then the early cable TV only channels came online like CNN, ESPN, and MTV - with ads.