Apple controls what may be installed on iphones with an iron fist. Did you know there is only one option for a web browser? Chrome, Firefox, and other apparent alternatives are actually re-skinned Safari. They don't want to allow real competition to their own browser. This is certainly not the only case where they use app store approval powers to block competition.
Plus Apple takes 15-30% of every transaction on iphones. That includes payments in the app store, and also in-app purchases. Sure they have to fund the store, but given that Apple has an absolute monopoly over iphone app distribution this seems predatory to me.
Apple is anticompetitive, and seems to have little regard for their responsibility as a platform provider to allow application diversity to flourish.
So Google has a similar app store approval process, and takes basically the same percentage from transactions. But they are much more generous in what they allow in their store in terms of competing apps. And most importantly, Google does not have a monopoly on Android app distribution. You don't need to do any jailbreaking to set up F-Droid, or to install apps from the web.
It's true that the vast majority of Android users use Google's app store. And I think that Google taking a cut of in-app purchases is also predatory. Apps should be able to not use Google Pay, and to not pay Google a cut. But the fact that there are other options puts a limit on how much Google can block competition, and gives some option for publishers to avoid that 15-30% cut.
The browser is a big one for me. 90% of what I do on my phone is in a browser, and even Firefox for iPhone isn't Firefox proper.
I already hate how much Google pushes Chrome in Android and doesn't let you remove it, but Apple dials it up to 11 and completely locks you out of any other options whatsoever.