I think people who are afraid to ask questions are conditioned to be that way. It is just easy to keep quiet in a team meeting than risk asking/saying something that might expose one's lack of knowledge on the topic being discussed. People also secretly hope that someone else might ask the same question that they are thinking about, so the other person can take that risk.

The environment largely shapes people's behavior. Of course, we can argue that we should work towards changing the environment for the better, but practically, how much influence does a person (who is not in a position of authority) have? In the end, people simply take the easy way out, which is keep quiet and only speak when they're absolutely sure that whatever they're about to say/ask is fully accurate.