Why do explanations of this problem never mention conditional probability, on which the explanation is based? There are dozens of videos explaining conditional

Why do explanations of this problem never mention conditional probability, on which the explanation is based? There are dozens of videos explaining conditional probability on youtube, but basically, the taking away of a door gives us additional information about the state of the system. It is counter-intuitive, but it's not a mystery. This principle is used everywhere to optimize real-world problems.