Developers of software apps for mobile operating systems are well aware of this and tend to focus on these two operating systems as a result. This makes sense from the developer point of view. Developing apps consumes a fair amount of resources such as time, money and effort. It does not make sense to expend these resources to develop an app for a operating system that has few, if any, users.
This further increases the dominance of Android and iOS. Since most developers of apps tend to ignore the other operating systems around, the latter have far fewer apps available. This makes people even more unlikely to choose a smartphone with an operating system outside of iOS and android because of the worry that a desired app may not be available for their phone. People simply go for iOS or Android to avoid any problems.
Difference between iOS and Android in terms of number of apps
With that said, Android and iOS are not exactly equal when it comes to apps. Apps are usually downloaded from a app distribution platform or app store by smartphone users. For iOS users, that would be Apple's App Store with no other alternative. For Android users, it's most likely Google Play, but it's not always the case as we'll see later.
While both are far ahead of the competition in the number of apps that they have available, Android actually has more apps than iOS. It is reported that as of 2017, Android's Google Play leads the market with 2.8 million apps. Apple's App Store is second with 2.2 million apps. Microsoft's Windows Store and Amazon's Appstore are third and fourth with 670,000 and 600,000 apps respectively.
