> People may realize that familial relations can significantly shape immigration process, but they tend to greatly under-estimate the extent.
I don't see any real evidence that's true, but, maybe it is.
> Immigration is almost always discussed in terms of fairness and, usually, "the line." But the metaphor is a bad one;
It's not really a metaphor at all, its a fairly literal description of the family-sponsored visa system which dominates immigration. At least as it pertains to the countries where immigration demand exceeds per-country quota, where qualified immigrants are literally on a wait list (in some cases one that will take a decade or more to reach them).
And I suspect it dominates the discussion specifically because the family-based part of the immigration system is the one most people know the most about.
> it might be better to think of the system as multiple, separate lines that are of varying distances from the destination.
Well, that would be even a more literal description of the family-sponsored system, since each category of visa has its own quota and queue.
Most of the rest of the immigration system doesn't really consist of lines...