Why are British so shocked by American support for the IRA?

Ignoring all the similarities between the Irish struggle for independence and the American Revolutionary War, there were plenty of reasons for us to support them. You go into Northern Ireland, declare a protestant state, you keep the Irish from legally having their own political party, you erase their political voice, you treat them the way the KKK treated blacks in the American south, you give all the good jobs to protestants...need I go on? Did the IRA do terrible things? Of course. There is always collateral damage in war. But if it wasn't for the IRA, the Irish would still be slaves in northern Ireland and you know it.