i know Myers Briggs isn't a perfect model, but it says there is a part of personality that is Thinking vs Feeling (this would be logic vs feeling). I wouldn't take thinking logically as a perfect or imperfect thing. Logic tends to lack empathy, so there are cases where logic isn't this perfect thing. Unless you'd consider someone's ability to consider people's feeling logical, then that answer doesn't apply.
So if tis moreso, why does it seem like some people aren't logical, than I'd say it can be a myriad of factors based on the situation. What's their emotional state? Are they under pressure or stressed? Do they have all the facts that they need to make a decision? Do they have too many facts and have to filter down to what matters? Is there only 1 right answer or are there multiple right answers? Is there only 1 path to any of these answers or multiple paths to any of these answers? (Apologies, I'm pretty dyslexic and my mind tends come up with 50 million questions, even when posed simple questions)