More accurately, to Cybertronians, earth is just kinda gross. Stuff is growing???? everywhere??? and you can’t escape it! There is like, nowhere on earth you can go where something won’t crawl inside you or stick to you or start growing on you.
Megatron briefly relaxes in the middle of a burning desert because he thinks he’s finally free or organics, for like ten minutes, and twenty scorpions climb inside him.
Don’t let them see what happens to shipwrecks in coral reefs and abandoned cars in jungles.
Also, don’t introduce them to kudzu. Or army ants. Or locusts.