Why is 'c*nt' so much more derogatory in the US than the UK?

Am I right in saying that in the US the primary usage of the word is for a man to call a woman a cunt as an accusation of reprehensible moral standards, as well as it being laced with undertones of misogyny and sexism? In this context, extreme offensiveness is very much the intent.

In the UK it’s not really used that way; rather it’s just another generic insult that, while still regarded as the strongest of our swear words, is losing its impact over time. As well as occasionally being thrown at each other by antagonists in an argument, it’s quite widely used between friends (men, predominantly) – either towards each other in a playful sense, or to refer to other people of whom the speaker disapproves.

So I’d suggest that different reception of the word in the two countries is down to these different predominant uses.

That's a very good question. It certainly is offensive here in the US, and I'm not sure why it's considered so much worse than other "Anglo-Saxon" words.

I've used all of the other ones on occasion. But in 52 years, I've used "cunt" anatomically only a handful of times, and I can't recall ever using it as a slang reference for a woman.

After Sen. John McCain called his wife Cindy a cunt in front of a bunch of reporters in 1992, they and their editors were paralyzed. The word is so offensive here, they couldn't figure out how to even talk about it indirectly, so the incident didn't become public until years later. In an American context, calling Cindy a cunt in front of strangers was so disrespectful and humiliating that I thought it was only slightly less shocking than if he'd punched her in the face, and I wondered why she didn't divorce him. I immediately decided not to vote for him in the 2008 Presidential election because, in someone of his position, it showed a frightening lack of self-control that's not compatible with controlling nuclear weapons.

In Australia it is generally not acceptable to use the c-word in female company as it is considered by many women to be derogatory of them. It may often be freely used in certain all-male company, but not necessarily as a derogatory term.

In Australia, cunt can be used quite freely, especially where it has replaced mate. For example,

Oi cunt ows it goin.