He's knighted, but Irish and can't be called Sir. I don't remember any of other non-British nationals getting a big "BUT YOU WON'T BE CALLED SIR." They said it in other terms and in other ways that were a little more polite.
I can see knighting Bono for the noble things he's done, but after they knighted Bill Gates it seems they'll just knight anyone.
Read about Bono's knighthood here.