I get that it's a regional thing. I don't think you need to know the underlying explanation just to memorize the term. Otherwise nobody would say things like 'mute point', or 'for all intensive purposes', or 'could care less', etc. Most people usually use the phrases in the right context, but clearly don't understand what they are actually saying or they wouldn't say it.

'Could care less' is imo the preferred formulation, the implication being that while there is no fundamental physical law preventing me from caring less, from a practical standpoint it seems highly unlikely. It's like how I could be a high lottery pick in the 2023 NBA draft - I'm unathletic and old and get humiliated by 7th graders in games of 1-on-1 - but technically it only takes one NBA GM seeing something special in me and I'm shaking hands with the Commissioner.

It's all in the delivery.