to do or not to do

I don't understand it when people say "sorry, but i am going to do this". Either, they are truly sorry in which case, they should not be doing what they were going to do or they do not quite care eitherways and are going to do what they are doing in which case, the sorry is a sham. So why apologise while preparing to do what you are apologising for? I am being too picky, eh?! Na, dont worry, these idiosyncrasies are not going to put me off. But one of these days when I am in a bad mood, its going to tick me off... :-)