Even back then, they were still businesses. Their customers were still the advertisers, not the subscribers. If there was dirt to dig up on a politician, they'd probably cover it. If there was dirt to air on the local car dealership, grocery store, or real estate brokerage--silence!
To be an actual public service, the agency relationship has to be right. It was never right for the mainstream media. Bloomberg terminals do have it right (I'm the customer, not the product), but expensive!