I've never heard of a cable package with CNN not on basic cable. You usually get CNN, Fox, and MSNBC. Dish network, the company who we're allegedly talking about, has all 3 on their basic service.
Also, the bonus for doctor's offices and car dealerships doesn't account for the success of Fox's prime time shows. Fox News routinely blows out its competitors in prime time, a time at which most of those businesses are closed and viewers are watching at home.
The people still glued to their TV sets and cable television in the US in 2014 are very likely politically and educationally uniform.
Admittedly with no data to hand, the demographic who watches FOX as a source of news likely anti-intellectual, science-denying, god-fearing, economically disenfranchised, and socially regressive.
But even if I'm mistaken in my gross stereotype of the audience for FOX News, judging the "merits" of a TV network according to the size of the TV audience misses the forest for the trees which is that in 2014 the smart ones aren't really watching any cable TV at all.
One guess where those smart people are getting their news. (Hint: the Internet has many, many sources of information where even single individuals can reach millions of people pretty much in real time.)