In 1972, George Carlin (Sadly, Not a Jew) had a very famous bit about "seven words you can never say on television". The words (just so we can have it on record) were "shit", "piss", "fuck", "cunt", "cocksucker", "motherfucker", and "tits".
40 years later, and not only do you hear every one of those words on television, you hear them daily. In various combinations.
So, what happened? Well, we can talk about America's loosening morals. Or the evolution of language. Or we can talk about HBO, the cable channel that also launched in 1972 and ushered in a new era of television.
For HBO allowed swearing. Comedian Robert Klein was the first to do so, uttering the word "fuck" in 1975. It's all cascaded down from there, to characters (Susie on "Curb Your Enthusiasm", anyone from "The Sopranos") or even a whole show ("Deadwood") where every second word is a swear.
And, slowly but surely, other television networks followed suit. Sure, there are still regulations, but to say that the landscape has changed drastically in 40 years would be an understatement.