Will Oremus has written a long article on OneZero (Medium paywall) that discusses whether Apple is an illegal monopoly or not.

Apple doesn’t allow apps to offer alternative payment methods and …

To tighten its grip, Apple prohibits the affected apps from even telling users how they can pay their creators directly.

Is Android an alternative?

Yes, Android offers an alternative. Yet with iOS users accounting for a majority of all mobile app revenues in the United States, developers have little choice but to create software for Apple’s products. “If you want to publish modern software, it’s essentially suicide not to have a presence on the iPhone,” Hansson told OneZero.

This is what keeps me from getting Apple products (apart from the price):

In reality, Apple has built its empire on customer lock-in: making its own gadgets and services work seamlessly with one another, but not with those of rival companies.

For example, I couldn’t use my Samsung Galaxy Watch with an iPhone to the extent that I could with my Xiaomi smartphone. If I had an iPhone, I would have to get an Apple Watch if I wanted to have a smartwatch.

I’m pretty sure Apple is abusing its monopoly, but Tim Cook disagrees:

By December, Cook seemed to be hedging his bets. While maintaining that Apple isn’t a monopoly, he mused in an interview that “a monopoly by itself isn’t bad if it’s not abused.” He went on, “The question for those companies is, do they abuse it? And that is for regulators to decide, not for me to decide.”