Perhaps by convention, it does mean that. This is the rhetorical inversion I spoke of. By the plain meaning of the words, it means the exact opposite. If you could care less, then you care more than the minimum possible. The phrase is the ironic inversion of the circumlocution, "I couldn't care less", which means that I care nothing, since it's impossible to care less than nothing.
So you see, rhetoric pervades all our expressions, and the plain fact is that there were no valid questions posed by the musings of GRETA HAGEN-RICHARDSON, your saying so notwithstanding.
Feel better now?