We'd use something like 'John takes care to do it', meaning that he is careful about ensuring that he does it. The 'it is careful...' idea doesn't work. It's not that it's ungrammatical, because the logic is fine; it's more a question of usage and 'it is careful of him' is not a natural pattern. Simply because something's the opposite in meaning, it doesn't necessarily follow that it can behave in exactly the same way.
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