why are these craters harder to spot on earth compared to the moon??

You see few craters on the Earth. Between the fact that 75% of the Earth is covered with water, and wind, rain, earthquakes, landslides. volcanoes and continental drift, the Earth's surface changes fairly quickly. From a geologic perspective, of course. The Moon's surface is dead. There are no volcanoes, no major moonquakes, no oceans. No weather; no rain, no wind. When a meteoroid strikes the Moon, it leaves a crater - and the ONLY way that crater gets disturbed is by another crater. You can bet that for every crater you can see on the Moon, there once were equivalent impacts on the Earth. But the Moon's craters are forever. The Earth is always rebuilding itself.