It's like having two car manufacturers and they both recommend "approved" gas where they scrape 30% of the revenue as a tax. Anyone that wants to make their gas "approved" has to pay 30% of the revenue.
The difference between apple and google is that Google hides a little switch in the glove compartment that lets you use any gas if you want to. Apple on the other hand will void your warranty and try their hardest to break your car if you dare use unapproved gas or try to modify the car to use it
You could argue that you could just not drive a car if you didn't want to pay extra for approved gas...
The core issue is that Apple has created a marketplace for something so pervasive in daily life and has a complete monopoly on it. If the marketplace was smaller or phones less important consumers could easily say "I don't like the rules" and walk away