OK, so that's one app from one developer, and Papermill requires that you have a separate subscription to Instapaper's paid service (which costs $1 per month). But Bateman's tale of disappointing Android sales is anything but unique. Mike Mobile makes games like . The company wrote that its "Android apps aren't making any money." In fact, the company says, "Android sales amounted to around 5% of our revenue for the year, and continues to shrink. Needless to say, this ratio is unsustainable."

Piper Jaffray analyst Gene Munster concluded late last year that Google's Android Market (since rechristened Google Play) . The App Store, Munster said, receives 85 to 90 percent of the total dollars spent purchasing mobile apps.

And we're talking about a of money: Apple says that it's paid out more than in the App Store. (Apple gets 30 percent of every App Store sale.)

Why the vast majority of Android customers don't seem willing to spend money on apps is anyone's guess. But it's a self-perpetuating problem; with lower sales, many developers are forced to upend the App Store's race-to-the-bottom for pricing. So now, the apps folks mostly aren't buying from the various Android app stores also cost more money.

But money doesn't explain everything. It certainly doesn't explain why it took Instagram so long to land on Android--given that Instagram is a free app, and its business model is largely still to be determined. No, the explanation for that half of the problem falls into...