If you fly a 747-400 for 16 hours, then you are out of gas. It takes experience to get to a big jet, but that doesn't mean that it is harder to fly. Does an RJ have autothrottles (or even FADEC active?), or autoland, autobrakes, or Cat3B approach capability? NO. The challenge is flying the airplane only once or twice a month because there are not enough legs to go around; which means that a pilot on these big aircraft require discipline and maturity. That is why they are getting paid more, they have been screened to be the best, are experienced, and can make good decisions - not because the airplane is harder to fly!