> One can be wary of, for example, the increased infrastructural strain of, say, large numbers of uneducated third worlders entering a country suddenly, without being hostile to or fearful of their culture.
As somebody who is passionately pro-immigrant, I haven't been shy of having this conversation with people. The whole issue of "infrastructural strain" is difficult to address in a way that feels non-adversarial, because the facts only live on one side of the issue. Every credible study has shown that immigrants are net contributors to the economy contributing far more to the tax base (and hence to the infrastructure) than they take in terms of services; the only counter to that is vague tabloid anecdotes that are quite transparently racist and xenophobic.
But facts like this do not matter in such a debate; people have an emotional discomfort with immigrants. When pressed, the defense ranges from "Fine, I don't have any facts to support beliefs; that's just what I believe" to -- perhaps more honestly? -- stories of how immigrants "aren't like us," how they "swarm like cockroaches", and "breed like vermin", etc. (Those last two from a couple of prominent Brexiteers whom I'd started the evening legitimately intending to befriend. Things got real honest after the second pint.)
So can one have "legitimate concerns" about "the increased infrastructural strain of, say, large numbers of uneducated third worlders entering a country suddenly" without being a xenophobe? In my experience -- and really, I've wrestled with this -- no. Not any more than one can have "legitimate concerns about conspiracies of international Zionist bankers" without being a raving anti-semite. In both cases, straight-up lies are being used to provide a cover of legitimacy for attitudes that are unquestionably xenophobic, and often virulently so.