Let's Get Something Straight

This has been a pet peeve of mine for a while and I would like to take a moment to clear things up.

If you are, for example, unfazed as to how someone else feels about something than the proper expression would be:

"I couldn't care less."

As in, you care so very little about their opinion that it would not be possible for you to care any less than you already do. You do not care at all, therefore you could NOT care less.

Now this seems fairly straightforward to me, yet I continually see/hear "I could care less." This makes no sense!!! This phrase signifies that you ARE able to care less about the given subject than you currently do. Which means that no matter how little you care about it, you do care about - which defeats the whole purpose of the proclamation! If you COULD care less then why don't you?!!??!

Now don't get me wrong, this is all about the context in which the phrase is used. If I were to say about my friends "I could care less," this would be true, because I care very much for my friends and it is possible for me to care much less for them. However the context in which I hear people saying it is "I am a fan of (band xyz) and I could care less what other people think." To reiterate: that means that you DO care what people think as you just stated that it is possible for you to care less than you currently do. ARGH!!!!

All right, I apologize for such a high and mighty rant, but populist bad grammar frustrates me.

UPDATE: History of caring less.