> The moral answer is open borders. Both capital, which is generally freer than people are, and people should be able to vote with their feet. However, this is unsustainable unless ..

A strong no on this being "the moral answer". If people are permitted to vote with their feet maybe people are also permitted to build pickets around communities. That sounds more "moral" to me than entirely ignoring the wishes of the chosen destination's "people". IFF the destination is happy to welcome people who think their community better than their own and want to move over, then fine, that is a much better candidate for "the moral answer".