BECAUSE.
Because lots of things.
Superman plays in a BIGGER arena.
They talk about how hard it is to write stories for superman on the animated series DVD, because you have a hero who is mostly invulnerable.
So the problem with writing movies about a character like that is there is a tendency to write " dirk dastardly" stories, wherein the villain kidnaps Lois, and ties her to railroad tracks to get at the hero.
We, as the audience have evolved past those stories. yeah, they're ok in moderation, but giving us that EVERY TIME is a pail of fail.
In my opinion, superman has a evil counterpart in lex luther, and not an enemy. I like the way they portray him in the Luther 5 issue miniseries.
He's a Do anything it takes to get it done businessman, who thinks he's looking out for the worlds best interests by trying to prove superman has some hidden agenda, Because He's an alien.
Superman REALLY only has two villains in his rogues gallery who are REALLY on the same playing field with him.
Darksied and Brainiac.
when they first introduced Him, doomsday was on that list, but not any more.