In general the largest craters on the Moon and Mercury tend to be considerably larger than those found on Earth. Why

Due to lack of water and atmosphere.

Explanation:

The largest craters on the Moon and Mercury are larger than those found on Earth because craters dominate the surfaces of Mercury and the Earth's Moon due to absence of water. Both moon and mercury lack liquid water on their surfaces that would remove the impact of craters with the passage of time. They also absence of an atmosphere on planets like the Earth and Venus, that could disintegrate meteoroids before they comes in contact to the surface.