They are very large and heavy (much more weight per passenger), there’s additional drag and resistance, not to mention time, which I think accounts for some of

They are very large and heavy (much more weight per passenger), there’s additional drag and resistance, not to mention time, which I think accounts for some of the energy waste. In short, that spending a few hours on a thin metal aerodynamic cigar is more energy effective than a week spent on a bulky floating city doesn’t surprise me.