Google is an advertising company. They make money from getting the advertising targets (you) to use their services, and charge the advertisers for access to you.
They're not going to make money off Android directly, it is just a way to get people on their platform.
This is why Google still makes iOS and Windows Phone applications. They just care that you're using their platform, regardless of how.
Apple is a hardware company.They make money from selling phones, and increasingly off of their app stores, but obviously not enough to open their app store to Google.
This is why you DON'T see iTunes, Facetime, or iMessage for Android. Their goal is to sell devices.
Microsoft is a software company. They make money off selling software, so they will, like Google, try to make their software available on as many platforms as they can. They, also like Google, care less about the phone sales and more about getting you as a loyal user of their products.
Unlike Google, Microsoft users are their customers.
Whenever people compare these three companies, they need to look at the core of who these companies are.
I'm not claiming one is better than the other, and in fact I use all three daily.
They just have different motivations for playing on the same playground.
It is somewhat like 3 kids all playing baseball together, but one is playing to be a pro baseball player, another is playing to have fun, and another is playing to impress a girl.
You can't compare the 3 kids to each other and say one is doing better than another, because each is measuring their success a different way.