I used to drive the 100 miles home, pre dual carriageways or M-ways. It took three hours every time. Being much young(er) then, I tried to cover the same route as fast as I could... I "saved" just 15 minutes. I must have used more fuel, tyres, brakes and engine life. (Possibly frightening others, too.)
Thereafter I took three hours.
An aircraft economist factors in the cost of time as well as fuel etc. At its crudest a tramp or Hobo is not in the same urgent need of speed as the millionaire.