They are part of a duopoly and I hope Google also gets scrutinized.
I believe non-Google Android phones are quite popular outside of the USA.
Every business is just a monopoly if you consider it alone, and a single 7 Eleven has 100% marker share among its store.
In your example, a consumer can easily leave 7-11 and go to a near by store at a much, much, lower cost than selling a house.
On Android, to have choices beyond the Play Store, all I need to do is change some setting and instal a 3rd party store.
On iPhone, to have choices beyond the AppStore I might be able to run some much more complicated and dangerous software, but only when Apple is behind in the cat and mouse game with jailbreakers.
The root of the question here is one we have to answer as a society. How much should consumer choice cost (relative to the price of the good/service they are choosing). Maybe 5x is reasonable, but 500x is not.
When a company deliberately does everything they can to raise those costs and thoae costs are very high (such as with Apple), I think we should absolutely call those companies to account for anti-competive and monopolostic trade practices.
This breaks down as there's no "physical area" preventing anything.
You can get an Android phone whether you're in Alaska or Miami or Tanzania. In fact it's easier, and most of the billions in the planet (including high income earners) do just that.
What exactly do you think the 'trust' in 'antitrust' means? From here[1]:
> A trust or corporate trust is a large grouping of business interests with significant market power, which may be embodied as a corporation or as a group of corporations that cooperate with one another in various ways.
> Until/unless the two companies are caught colluding against consumers