This saying really grinds my gears.

How did "couldn't" become "could"?

It inverts the whole meaning of the statement.

If you’re talking about something wouldn’t that always mean that you in fact ‘could’ care less?

Saying that you ‘couldn’t care less about X’ doesn’t seem logical at all because you of course could, ‘could care less’ is of course not particularly informative unless you’re expressing intention or a desire to care less about something.

> Saying that you ‘couldn’t care less about X’ doesn’t seem logical at all because you of course could

I think the whole point is that it means you don't care at all, and therefore it's not possible to care less.

But you are thinking and talking about that specific thing? Which means that you could care less.

The moment you say “couldn’t care less” you’re already technically incorrect because you obviously could..

Typically if you're saying that it's because someone else brought it up and you're letting them know you don't care.

The best kind of incorrect!

> How did "couldn't" become "could"

Sarcasm and Laziness are at least 2 reasons people might modify it. The second carries it through time.