For example a freelancer might charge $100-150 per hour. That's like $200-300k per year on salary (at that rate). But a freelancer at that rate doesn't actually make that amount, because you have to factor in downtime (they don't always have work, and they often have to spend time finding work) and they don't have benefits, etc.
Most of these job are for roughly 50 weeks a year, 250 days from 30 seconds of googling, of which all the "answers" oddly enough came from answers.com
That works out to 320 a day, and I know I am grossly oversimplyfying FICA taxes and other things, to the point where they aren't even being included.
So yes at 40 an hour for butt in a chair pay, some do better freelancing at times, and to some people the grass is always greener on the other side of the fence.