The usual health reasons I guess. And when I cook eggs in butter, most of the butter is discarded; I guess some could perceive this as wasteful.

I can cook an over-easy egg with less than a teaspoon of oil on a non-stick.

If I do it on cast-iron, it's easily twice that. That adds up to a lot of oil being throw away in a year. And while I love butter on bread, I don't want the taste of it with my eggs.

Maybe you could use less butter? When I cook eggs, the butter is basically all absorbed by the end. It took a few tries to dial in the perfect amount though.