It's not an error if it becomes widely adopted. In the UK "I could care less" isn't used, but if it's common currency in the US it's unfair to call it an error. Personally, I can't get my head round how it's supposed to make sense but I still hesitate to call it an error. I've been castigated by several here for criticising the nonsensical "albeit" (all be it? Although be it? Although it be?), which equally doesn't make sense, but it's widely used, especially by those of pretentious inclination, and there's no way I can call it an error.