This is very true, and I think it's worth noting that there are few circumstances where you have less basis for confidence than an interview. You're inherently conforming to someone else's workflow and being asked to respond to significantly unexpected, low-context questions.

A code review or client meeting involves defending decisions that you or people working at your company have made, and explaining things for a code base you ought to have at least some familiarity with. That's a far different beast than being asked with no warning to come up with a way to complete someone else's task in a way that they consider "suitable".