This kind of flight has to be an oddity else BA would go bankrupt. On average a 747 gets better mileage per passenger than a Toyota Prius and it does it traveling a direct route at 550mph. Also mileage has greatly improved over the years and is set to get better with carbon composite aircraft. Jet airliners are an amazing green technology.
What really is going on is the greens are green with envy that people are going on vacations and money making business trips and they aren't. A leftist cannot stand it if anyone anywhere has it better than they do. They make their happiness contingent on nobody being happier than them.
You said a mouthful there. I agree 100%
I was somewhat shocked when a coworker told me (and then showed me the math) that a 747 gets about 5 mpg at cruise even when fully loaded. Getting up to cruise takes quite a bit more, but once it's up there, it really doesn't use that much fuel.
Compare that to my old Suburban that got 9 mpg dead empty (except the overweight driver). With a tailwind. Downhill.