More specifically, I hate “American English” computer dictionaries. I am about as English as they come, I watch Rugby, I listen to cricket, and I get depressed and irritated over the form of my Football (No, not Soccer) team.
And so, it really gets my bloody goat when every single piece of word-processing software I’ve ever own underlines a load of words in red just because it can’t cope with the existence of the letter U.
There is no such thing as American English. There is English, and there is wrong.
On a serious note, I’ve chatted with people around the t’interweb who have had their books flagged for typos because they weren’t in American English. This is what is colloquially known as a dick move. don’t do it.