I think
@ssu is on the right track. A lot of this has to do with power.
A couple things that come to mind. (Focusing only on one aspect here. I think it's more complex than this.)
(1)
Potlatch. In showing generosity, one enhances one's own prestige. Potlatch increases one's prestige because, in order to take care of others, one has to have at one's disposal resources far in excess of what one needs to take care of oneself (or family). So the feast is symbolic, but a weird kind of symbol. It's a symbol that symbolizes one's capacity to create the symbol. Sort of the same logic behind diamond rings - they don't just symbolize love, they display, in-and-of-themselves, that the lover has the means to buy a diamond ring (and the means, by extension, to take care of the beloved. )
Both potlatch and diamond rings reinforce existing power differentials (or shift them to the advantage of those throwing the party). To give 'selflessly' is also, often, to say : You need me more than I need you. Which is also to say: It would definitely not be in your best interest to threaten my power, or to find a source of power for yourself. (The inherent connection between diamond rings and patriarchal norms and the independent heroines of 19th century novels dying in squalor )
(2)
For each and every virtue tied to economic and power differentials, there corresponds a 'spiritual' one.
"you can't provide for others unless you can provide for yourself."
"How can you love someone before you love yourself?"
The familiar Hegelian and Nietzschean point that many of the more ethereal virtues are direct inversions of earthly ones. Epictetus, the stoic, was a slave - 'slave morality.' "You may have power over me irl, but I have power over you
in my mind. " Later, the marxist point that bourgeois sanctimony conceals actual exploitation. What still matters, ultimately, is economic power - only now lip service has to be given to its opposite. To the point where people are genuinely confused about what they value (disconnect between behavior and professed values.)
(3)
Those who are pro-immigration usually discuss the issue in those ethereal, moral terms. It's true that they focus on what immigrants lack materially. But the guiding idea is generally that it is good/humane to provide for those who lack.
Those who are anti-immigration usually come at the question in terms of physical, economic and scoial security. They are worried about crime, loss of jobs andoverburdening the welfare system.
Both arguments exist along a spectrum. At the hyperbolic end of the pro-immigration side, you have those who want totally open borders and seem to display symptoms of spiritual megalomania. On the anti-immigration side, you have open racism and seething resentment.
Both sides often slip into characterizing the other side in terms of that side's most hyperbolic proponents.
(4 - the main thing I want to get at.)
There is way of excluding others, quietly, through quiet signs. What allows one into highly exclusive, or partially exclusive subcultures? Just south of those groups inclusion in which requires very Old Money, its usually manners. Ways of talking, or other of the 'critical social graces'
@Bitter Crank spoke of. It seems like belonging to a group which won't take in just anybody is crucial for some part of the human soul. In the same way you can't really feel loved by a lover who would just as easily love someone else, you can't feel like you belong to a club that would include everyone. So, like you said, identity (especially in the mode of belonging-to) is built on exclusion.
Back to potlatch. Those who are most of assured of their own exclusionary clubs are those who will most freely dispense that generosity of spirit which excludes exclusion itself. Those whose aren't are going to get nervous and defensive. It seems to me (caveat: no studies conducted, or even consulted) that pro or anti immigration views usually correspond less to income than to
social security. For those who have it, its often invisible, taken for granted. In the same way Kant talks about the transcendental conditions of perception, we could talk here about the social conditions of the virtue of inclusivity.Perception can't perceive its own conditions; It's only through reason that it's able to reflect on itself. In the same way the virtuously inclusive are often blind to what allows them their virtue.
And, because of this, they have no trouble seeing their virtue and moral judgments as exemplifications of a universal virtue ethics or a universal moral matrix which can - and should - be applied to everyone. Again, this is similar to Marx's criticism of bourgeois morality.
(5)
If there's always, inherently, a kind of social power differential in play when it comes to providing for others, then there can be no universal moral answer or heuristic here. While there any many patterns that repeat, the specific power dynamics of any place are complex and singular. The knots of reason come when, from consideration of one particular situation or set of situations, there is extracted a universal ethics, which is then turned around and applied to all situations.