Android can't force developers to do what they want, that's kind of the point of the competing-implementation idea. Google has been tightening that back down somewhat, but they don't have a lot of ability to compel anyone to do anything.
Apple, on the other hand, retains an absolute monopoly in their section of the market, and can impose any terms they want. It's their way or the highway. Anyone who buys into iOS or develops for iOS must comply with Apple's demands.
Again: don't confuse monopolies with markets. Apple is able to compel developers because they are a monopoly within the broader phone market. Google is not, and can't.
Where did I say ‘compel’? We’re talking about market dominance not monopoly power.
You didn't. But Apple's various technologies are things they
force on developers, so of course they get better uptake.
If they were truly market dominant they wouldn’t have to compel anyone. Developers would want to preference their platform because it’s in their economic best interest. Consumers would want to spend more to get access to the platform (increasing ASP). Accessory makers would want to flood the market with accessories.
But their status as a monopoly (even though probably not in a legal sense) totally messes up that argument. You don't really buy an Apple phone. Instead, it's like a combination of rent and ownership, where it's always the worst interpretation for customers. Customers own the phone when it breaks, but they're only renting the phone when they want to just use it.
Developers
do want to preference iOS because they make more money there, but if they want to exist in that walled garden, they
must embrace and use the technologies Apple wants, and none of the ones they dislike. Otherwise, they cannot gain entry. Consumers
must buy only Apple-approved software. Accessory makers
must get licensing and approval from Apple or, in most cases, they cannot sell their devices, unless they're very simple.
So the Apple phone market
is not like other markets. You can't directly compare with it anything else, because anyone involved is forced to comply with Apple's wishes. They don't get a choice.
Google's market, on the other hand, is far more lax. If you're willing to sideload apps, Google doesn't get a veto over what you use. And, for the most part, they don't force developers to do any particular thing to exist on Google Play, probably because of the first thing... if they're too draconian, people can just install other apps and other app stores without permission.
Google's market, in other words, functions much more like a classic market from economics. Apple's is totally different. Directly comparing the two doesn't work very well, because Apple can physically set the rules in a way that Google can't.
How can you call Android dominant as a platform if it has none of the hallmarks of a dominant platform?
Because Android sells more phones to more people than anyone else? More people are using Android, by far, than iOS. By classical market definitions, they are dominant. You're mixing in Apple's monopoly powers and pointing to those, but their market is not even remotely free.