(S)he tries to become just another lost tourist, though she knows she'll never be one.... Cayce knows that she is, and has long been, complicit. Though in what, exactly, is harder to say. Complicit in whatever it is that makes London and New York feel more like each other, that dissolves the membranes between mirror-worlds.You know how in Star Trek whole planets share one culture, one worldview, one way of dressing, even? The Klingons are all honor-obsessed and warlike, the Vulcans are logical and unemotional, the Romulans all wear shoulder pads.
Pattern Recognition is (and if my memory and clairvoyance, respectively, are correct, Spook Country and Zero History are as well) about a planet, ours, in the process of developing itself into one of these monocultures. One thing Gibson captures admirably is the terror of being caught in the middle of this, and the unwilling ambivalence many of us feel about it all--wanting to find the whole thing atrocious, wanting to oppose it with every fiber, but being unable to resist the appeal of the fripperies of globalized consumerism, and unsure of what to do about any of it, anyway.
The next sentence, incidentally, is this: "She knows too much about the processes responsible for the way product is positioned, in the world, and sometimes she finds herself doubting that there is much else going on."