Everyone knows this, the problem is that very few devs straddle the iOS/Android fence, and therefore are more familiar with one platform than the other. While most devs might know that conventions are supposed to be different, few have a deeper understanding of what is necessary for actually implementing each. Someone who truly understands both platforms and treats them accordingly is quite rare.
...well then give me the hardware or some unique OS feature set to exploit! Right now I'm doing a quickie hello world app which will be a simple multimedia book for a tablet. Just putting the specs of the most recent iPad side-by-side with a Kindle Fire is just depressing.
Or even if the feature sets are pretty much the same focus on ease of use for getting my foot in the door. For example why isn't there something like HyperCard so non-programmers can create apps for Android? Not for nothing Visual Basic had a huge impact on making Windows a standard for inhouse IT dev.
App Inventor looks cool -- but in terms of interface and usability it just isn't HyperCard. It's honestly amazing to me that since 1987 nothing much has come out to top it in terms of ease of use. I really LOVED that program...
The single biggest one is how Android apps are structured. iOS apps are effectively monolithic enclosed islands.
The structure of Android apps is that they are mashups. This covers not just the UI screens but also data, processing and events. Not only should your app be a mashup internally, but you can include components from outside the app just as easily as those from within. And you can make your components usable from outside your app so that other apps can be better because of your components.