I don't know why Apple "goes white" but what do you mean by "the rest of the industry"? Do you mean cables bundled with products like smartphones or tablets or cables sold as "standalone" accessories? Well, black is dominant, I suppose but e.g. I have one white and one bright green micro USB cables, I had a grey mini USB cables bundled to my mini DV camera. My wife once had a pendrive with USB extenstion cable which was silver (in fact a metal screen on the cable covered with transparent plastic).