The visibility of different phases, such as the crescent phase, depends on the relative positions of the Sun, the object in question (Venus, the Moon, or Mars), and the observer (Earth). Here's an explanation for why we can see a crescent phase on Venus but not on Earth's Moon or Mars:
Venus: Venus orbits the Sun closer to the Sun than Earth does. Since Venus is an inferior planet (its orbit lies inside Earth's orbit), it can exhibit phases similar to those of the Moon. When Venus is on the side of the Sun opposite to us, it appears fully illuminated (similar to a full moon). However, as Venus moves closer to the Sun in its orbit, it starts to exhibit crescent phases as seen from Earth. This occurs because the illuminated portion of Venus visible from Earth becomes smaller, resembling a crescent shape.
Moon: The Moon, being Earth's natural satellite, always remains relatively close to us in our orbit around the Sun. The phases of the Moon are determined by its position relative to the Sun and Earth. When the Moon is positioned between the Sun and Earth (known as the new moon phase), the illuminated side faces away from us, making it invisible or very faintly visible. As the Moon moves along its orbit, it gradually becomes more illuminated until it reaches the full moon phase, where the entire side facing Earth is lit. The Moon does not exhibit crescent phases as seen from Earth because it is not in an orbit around the Sun that places it between the Sun and Earth.
Mars: Mars, like Earth, is an outer planet whose orbit lies outside Earth's orbit. As a result, the phases of Mars, as seen from Earth, are less pronounced. Since Mars never comes between the Sun and Earth, it does not exhibit crescent phases like Venus does. Instead, Mars appears as a small disc in varying degrees of illumination, depending on its position relative to the Sun and Earth. The brightness and size of Mars can still change due to its elliptical orbit and varying distances from Earth.
In summary, the visibility of crescent phases depends on the relative positions of the Sun, the object in question (Venus, the Moon, or Mars), and the observer (Earth). Venus exhibits crescent phases because it is an inferior planet with an orbit inside Earth's orbit, while the Moon and Mars, being in different positions in relation to the Sun and Earth, do not show distinct crescent phases.