I was going to quote CIG, but I feel like the discussion of cultural appropriation is gravitating toward very specific and quite unhelpful examples such as costumes, which I realize I brought up. I don't think this helps to address the original comparison of cultural appropriation to a kind of "open borders" mentality, i.e. the liberal transmission of cultural forms across cultural boundaries.
I feel like I shouldn't have used costumes because it really doesn't get at the complexity of cultural appropriation and is too hot-button. The actual scholarship that I've read on cultural appropriation isn't on fashion but on literature, and what happens here is far from the kind of cultural appreciation that some argue for in fashion. In literary history, cultural appropriation usually takes the form of (generally speaking) the transmission of specific texts across cultural boundaries which are substantially altered--linguistically (obviously), ideologically (less obviously), and sometimes formally (slightly more obviously)--so as to obscure or sometimes erase the original cultural function of a particular work. When this happens, the work comes to represent certain values that may not correlate to those of the culture of origin, and that may in fact be used in opposition to the culture of origin.
Furthermore, this describes cultural appropriation not only in terms of white and non-white, but in its more appropriate context of cultural domination. In this respect, we can observe cultural appropriation occurring between, for instance, China and Japan, or Africa and France, or black folk culture and white American music (to give a few examples). It isn't always between white and non-white, and this isn't the sole focus of those who write about cultural appropriation in academia.
I'm concerned with the ways that appropriation alters the values associated with a particular cultural form in such a way that the culture of origin suffers due to the values perceived/imposed by the appropriating culture. I do believe that can happen with costumes, but the scholarship I've encountered deals with literature. Obviously, literary criticism attempts to overcome (or at least acknowledge) these barriers as best it can, but it still reflects on historical interpretations/translations, which gave rise to (for example) Western myths of the "noble savage" and the "primitive pacifist"--both of which have been shown to function in ways that reduce, demean, and deprive the cultures to which they're attributed, and that reveal some underlying proclivities of Western cultural values.
As I said, costumes don't quite get at this less visible yet, in many ways, more extensive network of appropriation.
As this relates to cultural appropriation = open borders (for the sake of argument): I think this is true. But as I've said in other arguments recently, open borders also correlate to the most faithful realization of a free market, that being a global free market. This is not to say, however, that in such a scenario all parties will remain equal--far from it. In a system of purely deregulated capital, wealth will absolutely accumulate in certain areas and vanish from others, leaving certain parties in the dust. Likewise, cultural appropriation may indeed resemble open borders, but it also inevitably yields inequity among the parties appropriated.
not going to happen dude
