Google's Android operating system has long suffered from a problem called "fragmentation."
Unlike with the Apple iPhone, it's up to smartphone manufacturers and not Google itself to push out updates to customers. So there's no guarantee that any given phone will get the operating system upgrades.
There's also a ton of different hardware, some of which does a better job supporting certain features. Contrast this with Apple's very few different hardware choices.All this makes life a nightmare for anybody making Android apps: There's no guarantee that an app that works on my phone will work on yours, or vice versa. Multiply that times the many millions of Android devices out there, and it's a minefield of apps that may or may not work for huge segments of your potential audience.