But I do find it ridiculous that a lot of people (including lawmakers) want to force Apple to open its store, but defend Sony/Xbox.
No. From a legal standpoint, there's no good reason to treat a $499 consumer CPU+GPU device differently, depending on whether it sits in your pocket or under your TV.
If you support government-mandated third-party app stores for your iPhone, you should support them for PS and Xbox as well.