But that's not fair because city population should be taken into consideration, not server population, won't you agree?
You missunderstood. Server population isn't a factor into the calculation of the consumption. But if a server is more populated individual cities have more players too. And cities level faster cause there are more players hauling. And then the dynamic cunsumption calculation increases the consumption. Especially the time component hurts. You'll the a big difference of the consumption in your city at level 3 between day 2 and day 3 of the era.