Of all the big tech companies Apple is the most innocuous. There have no monopoly in any of their sectors and you can just ignore them if you wish, as I do, without any consequences.
There is at least one aspect where they may be a serious competitive problem: their enormous size enables them to buy up a huge share of the world's most advanced chip supply from TSMC. Their scale and the profit that goes with it makes that possible. They can very effectively limit competition globally through that mechanism.
You're a smaller company with a hot new phone? You need a large supply of 3nm chips from TSMC to compete? You can't get them because Apple is buying them all.
And their leverage on TSMC (with TSMC eating the cost of defective supply), which is very remarkable unto itself, may also be a serious problem.
It's not just testing on them. If any of your customers have bought an Apple mobile device, your only feasible way to distribute apps to them is through Apple.
It's like having Comcast and Time Warner and they each want to charge 30% of revenue to any service traversing their network. Not only is it unreasonable to say that they compete with each other because if you're not satisfied with Comcast you can just sign up with Time Warner -- because one of them is in California and the other is in New York and you'd have to move -- but it's not even you who would have to move. The customer of the App Store, the one who pays the fee, is the developer. It's your customers who would have to move -- every single one of them, or Apple still has a monopoly on each one who doesn't.
Notice how this differs from an ordinary retailer. Your customer can easily go across the street to Target or Walmart, or shop in both stores on the same day. They don't have to "move" -- buy a new device for hundreds of dollars and transition all of their other apps and services to an incompatible platform.
