The report doesn't seem to break this down into iPad vs phone/pod which is annoying. I use my ipad for purchasing but very rarely my phone, but maybe this is unusual.
I think the iTunes gift card is a huge factor in this. Anyone in my family who owns an i_____ device receives these things routinely for birthday/Christmas gifts from relatives who don't get them something personal. The Android market doesn't have gift cards in your local Walmart/Target/whatever for people to just easily pick up as gifts.