If Android has sold all those phones, why aren't they used?

I have a web app that I've sold to three entities just south of San Francisco. I track (using Google Analytics) the visitors, partially so I know which browsers I need to test against. I think I wasted my money on that Nexus 7.

When I look at the mobile tools used to access the site it's surprising to me that iOS (iPhone and iPad) are so far ahead. There's a thought that iOS remains the more attractive platform to developers because people actually use the phones for more than just phone calls. 

(And yes, I know there's not a thing called 'Android' selling all those phones. But you know what I mean.)