Unfortunately, dear hotspur (may you have peace!), "we" Americans say a lot of things incorrectly. And we spell poorly. And our knowledge, understanding, and use of punctuation is seriously lacking. It's because we're usually very rushed (or simply don't pay very well attention) and so drop a word or two, leave out commas, and mispronounce... forgetting that doing so might actually change the meaning of what we're trying to say. In this case, dear CultC is right: the correct phrase is "I couldn't care LESS." Meaning, I am at the bottom/end of caring about the thing and there is nothing I could care LESS about. In contrast, to say, as "we" often do, "I COULD care less," means, of course... my caring COULD be less... about this or even another issue.
People here tend to think it, well, arrogant (er?) if someone mentions/corrects/asks questions about their poor grammar, bad spelling, misspeaking, etc. I found that to be especially true while in the Borg. Folks there (especially pioneers and elders) tend to have some kind of revulsion against anyone who appears "learned". Indeed, they are only accepts as "learned" if they're (1) white, (2) older(er), (3) married to an educated unbeliever, (4) educated before they came in, or (5) had some rich relative who demanded they go to college or lose their inheritance. Regardless of their education and/or background. If they don't fit into one of those categories (and, being black, I never did/could), then they were "being immodest," or some melarkey like that. Unfortunately, the WTBTS knows this... and exploits it. It WANTS its members uneducated for a reason. Think slave masters. Indeed, if they could limit school attendance to the 8th grade, they would. Maybe even less.
And so... I stopped caring about it a long time ago. They kinda made me. I just keep check on myself, but as for anyone else's poor phrasing, etc., I really... couldn't care less. No benefit in it anymore.
Again, peace to you!
A slave of Christ,
SA, who understands the "danger" in letting stuff like this go... as shown by the WTBTS' control over its members as a result...