If users and developers prefer other systems they can simply use those.
If Apple prefers anticompetitive practices, it can simply only do business in those regions.
Presumably, before they take such a drastic measure, they would first spend massive amounts on lobbying, which would most likely succeed.
What would actually happen is that the US would start seriously threatening (blackmailing) the EU to a degree where it's forced to relent long before Apple would pull out.
Apple's estimated operating profit from the EU is around $40 billion dollars. If the US government wouldn't get involved, they could force Tim Apple himself to live on top of the Alps and he'd happily do it rather than lose that $40 billion, or shareholders would vote him out ASAP.
However, the counter argument that opening iOS to other stores and payment methods would not affect users who prefer the App Store is not necessarily true either. If developers can choose not to distribute via Apple's store to avoid restrictions that are unfavourable to their business model then users would no longer be able to buy those apps in the App Store.
This is the dilemma that needs to be solved.
One solution could be to adopt a rule similar to the one for social logins. If an app supports any social logins at all then it must also support Sign in with Apple. Unfortunately, adopting a similar rule for the App Store is a lot more complex.
If an app rejected by Apple is then not allowed to be installed via an alternative app store either, Apple would once again be able to veto apps for whatever reason they want. And if developers were free to set a any price they want for each store, they could effectively make the App Store unviable.
I still feel that there is a set of rules that could make this work. The complexity is unfortunate though.
You mean, the Google system that collects 20 times more telemetry than the iPhones? https://news.ycombinator.com/item?id=26639261
