There's clearly a substantial expense involved in setting up Aetherites. So much so, they've had to be invested in, and now fees are charged to use them. Which suggests that there is widespread use of them. But that does beg the question of why I'm running quests to rescue U-tribe hunters from Amalj'aa cages; couldn't those girls just "return" out of them, back to the Aetherite at Forgotten Springs?