Ahh. Well i think you can explain a great deal of biases by the brain simply not being all that powerful and how it has to rely on various simple strategies rather than direct foresight and maximization of some foreseen quantity.

You can't really expect a person who can't do monty hall problem, to do proper probabilities - and that's the majority of people - and then, you can't expect a person who can do monty hall problem, not to pick up various cognitive and behavioural habits from those who can't. Then, why people can't do monty hall correctly, is it some universal failure in the brain organization? Well, smart individual would figure it out, most individuals can be taught methods for figuring it out.