Quote from Ted D
Not to belittle rehab or mental health nursing, but isn't there a lot more critical thinking and stress involved for a nurse in the critical care setting?
Come work the psych emergency room with me for a while, then tell me what you think
Seriously, it's all apples and oranges--different specialities, different environments, different skill sets. Same important outcome though: (hopefully) a safe and recovering patient. For the most part, you really can't say that specialty X involves more or less skills and CT than specialty Y. I personally think the toughest specialty to work is LTC, but that's a story for another thread.
I'm more inclined to agree with llg and KelRN. It's probably more about supply and demand than it is about the specialty itself. It seems like everyone wants to work ICU/ER/L&D/other high-profile areas, but not as many want to work in other specialities...so there has to be something extra in the carrot dangled to lure them over there.
It's also probably very facility specific too: a big hospital with lots of applicants probably doesn't feel the need to pay as high wages as a smaller facility/setting might have to in order to attract staff.