I'm not convinced that the reason people on Apple devices are more willing to pay is because it's harder to pirate. Piracy on Mac is just as easy on Windows, but the typical view is that, like with iPhone vs. Android, Mac users are more willing to pay than Windows users.

I think the real explanation is that there are a lot of cheap Android devices throughout the world, and people who are trying to save money on devices also try to save money on apps. I suspect that if you look at the piracy rates for just the $1000+ Android devices, they won't be that much different than for the $1000+ iPhones.