A great many reasons. I grew tired of explaining them to fanboys on the internet so I’ll explain the problems here. Your comments are more than welcome, as is your feedback on my proposed solution.
1) Market Share.
The tablet market is split 60%/40% – IOS / Android according to the latest figures I could track down. This means that the largest single chunk, is resoundingly in Apples garden.
2) Fragmentation
Apple tablets are a single system. They all have the same size screen, one of two resolutions and predictable hardware. Android devices do not have *any* of these benefits as you can see in these info graphics. Designign for them is much, much harder as you have to account for so many more variables.