Would you say English is a careless language? I think the opposite is true. English is a careful language in that its most practiced users choose words with specific intent, to ensure their purpose of meaning is clear.
However, sometimes the users of the English language are careless and use words incorrectly or worse, inappropriately.
The very statement “I could care less” as an expression of how little you concern yourself about the possible demise of someone, is used incorrectly due to laziness.
Over time the language develops and changes, but it also suffers from misuse. The lazy aspect in this statement is that “not” has been dropped.
The correct statement is “I could not care less”. This means if your care was placed on a graph and 10 was caring the most and 1 was caring the least, at 1, “You could not care less”. Here your caring capacity is so low, it could not possibly be less.
But at 10 “you could care less” given that at this high level your capacity to care is so high that it could be lower still. This means that you care some amount, but could care less still. But ultimately you still care.
Be careful with the English language and use it with care. You don’t want to be caring when you definitely don’t care at all.