Tim Kinder
Somewhere in the gap between time and eternity...
I've seen it used as ' I could care less' in books published in America, and thought it must be a difference in American English, but I see you're from Ohio. In the UK we would say 'I couldn't care less' as you say.
It may well be an Americanism to say "I could care less" I just call it laziness of speech. I hate the degradation of speech and words into acceptable slang regardless of proper meaning and form. Words mean something; they are meant to convey a point with a meaning.
Not going to say I don't use some slang occasionally. We all do. But when you hear someone slurring together improper words into nearly incoherent sentences, it irritates me something awful. It's especially hard to watch most TV interviews with people off the streets and listen to them attempt to speak.
It's a sad, sad state of affairs.