Why do some regions near the Moon’s poles remain in permanent shadow?

Because their geography shields them from direct sunlight due to the Moon's fixed orientation.

The reason certain areas near the Moon's poles experience perpetual darkness is fundamentally different from the horizon effects seen on Earth. On the Moon, the cause is geometric and tied to its fixed orientation relative to the Sun. Some regions, often within deep craters near the lunar poles, are permanently shielded from direct solar illumination because the angle of the Sun never allows light to penetrate into those specific geographical depressions. This state of being shielded from light for billions of years contrasts sharply with Earth-based polar observations, where the Moon is temporarily unseen due to its orbital path dipping below the local horizon rather than a complete absence of a light source.