iOS and Android are neck and neck in the US. There was a report about iOS passing Android just days ago, so they have similar market share. I can readily believe that at certain workplaces, almost everyone has an iPhone, but this isn't true generally.
I'm sure it does depend on your community too, e.g. iPhones are more common among members of the upper-middle class. (Which is why iPhone use is well above 60% in my social circle.)
This is the reason I haven't switched to Android—so it has worked on me at least.