Power
Batman. Captain America. Wonder Woman. These super-powered illustrations have some serious pull in modern American society. Besides being able to fly or leap over buildings and stuff, the characters in every frame of the comics are also world-famous role models for people everywhere. If Wolverine were a real person, he'd be elected President—oh wait he's Canadian...
Those heroes have power. But the people who illustrate the comics? They're just happy to have DC or Marvel paying their salary.
An illustrator's power has a lot to do with their reputation. If you have a strip in dozens of Sunday newspapers, you can negotiate for good placement or higher pay. If you're just selling your sketches on the side of the street, no one's going to invite you to any high-stakes illustration meetings any time soon.
There's one job for an illustrator that does play power politics—the political cartoonist. You'd recognize those from the oddly-drawn people and buildings with topical words like national deficit and Iran written on the sides. They have a point—we're just not always sure we know what it is.