This is the trouble with grammar police who desperately try to cling to some past meaning that probably never existed anyway. Could care less and couldn't care less have nothing much to do with the individual words. You simply have to take the constructions as a whole. I won't dwell. The other thing is that both expressions are wot millions of people say. When millions of people say something, and have been doing so for a long time, then that something is standard English. Either live with it or make yourself miserable. Your choice.