If you're independent, then you've got quite a bit of power. Sort of. That is, if you want to shoot sunsets, hoping someone will pay you for those photos, then you can work wherever you want to work. You can order yourself around all you'd like.
If you're shooting models, you get there at the agreed upon time (minus twenty minutes—you'll need time to set up). If you work for another photographer, studio, magazine, or the like, you'll pretty much have to do what they tell you to do.
As far as power goes, though, t-t-that's all, folks.