He has a learning disability, has never been to the US and committed his "crime" in the UK. Any government with a speck of pride or self-respect would have told the Yanks to go f*ck themselves.
And there lies the problem. Blunkett secretly signed an extradition treaty allowing the USA to extradite Brits, however they won't give us the same treaty to extradite from there to here. It seems the gov't are too concerned about metaphorically sucking off america rather listening to what the general public want.