When he sees something out of the norm, he will inquire. However, unless there is an impetus to inquire, no query will be forthcoming. For this reason, he is termed Simple. The She'aino Yodai'a Lish'ol, the One Who Does Not Know How To Ask, is simply not as smart as the other two. Even when he sees something that is unusual, he will not inquire about it.
Oddities are no inspiration for education.
He just does not know how to ask even when questions are most definitely appropriate. The Rasha, the Wicked Son, is on par with the Chacham. He is smart. He does have a drive for the bigger and better. However, his drive is motivated by a desire to do evil.