Because , Correct me if I'm wrong , But isn't it quite a straight forward thing to port an app from android to iOS ? Or am I going crazy ? I was under the impression tools are available to make it not that big a job ?
Well, the two ecosystems are very different. Java vs Objective C, virtual machine vs compiled, etc.
Porting may be easy if you use some kind of framework (like Qt for example) but it will make the app much bigger and huglier. If you wanna do a nice app with native android looks, it will be nice and good but, in order to port it to IOS, you must rewrite the most part.