I don't see a way in which Apple is abusing its monopolistic threshold within its competition. Apple slides in at 45% of phone purchases in the US market. That's 122 million people choosing something else. Now, that's not marketshare, but Apple has convinced consumers that their product is worth the markup - clearly evident by the increased marketshare.
I don't understand the desire to regulate a business that has clearly demonstrated value in a highly competitive market - if you don't want an iPhone, join the other 122 million Americans or 2.3 Billion people with an android.
_You_ may believe
> Q.E.D. Apple has monopolistic power in the U.S. and needs to be dealt with.
but by and large, monopolistic control and anti-trust cases are only brought to court if they are used to negatively impact consumers. In Apple's position, they believe they are doing the better thing for the consumer. If their argument holds water in court, then who is the US government to tell Apple if that business strategy is sound? If the market wants something different or better, then it will decide.
Things would be different if Apple were attacking other platforms, but instead, they're simply moderating their own.