Why do you think the devs put the extreme cargo limitations on them? You still do make a huge profit doing whatever route you want, though. Or just get a slaver Id and a 5k, nothing on that ID says you cant.
Dont try to compare a SPACE game set in ~3500 A.D. ( if my failure math is correct ) to real life. Its nothing like it. Its IMPOSSIBLE. Its just like comparing WW2 to the Bombers vs. Cap bull. Doesnt work. If that was true, we'd have bombers flying into caps and them dying in one hit.