This isn't rocket science: audio goes into mic => STT engine => translation model => TTS engine => audio comes out of speaker. As a fellow hacker here, you could piece together something like this in a weekend on your computer for fun.
As for your question though: they can charge a subscription for using their LLM if they want, or charge for this specific app/feature of iOS. Or just be like me: whenever I'm about to execute on a business plan, I ask myself: "Is this business plan economically feasible without breaking the law?" And if it is not, then I do not do that plan. So far I haven't been cited for illegal conduct by any unions of dozens of countries, so it appears this tactic works.
They could easily make this live translation feature a separate app using publicly available iOS-APIs. Every competitor would be able to develop and provide the same feature.
Ah, not integrated enough for them? Fair enough, then whatever further integration they see fit needs to provide interoperability for competitors.
That's exactly the stance of the EU DMA.
your post doesn't even get close to the subject
Perhaps the issue you seem to be having is that there's nuance in a position which tries to see an issue from both sides. Whatever is the problem with your comprehension, I advise you to reflect on the fact that others in this thread seem to get it and some have raised valid counterpoints or added relevant information.
Remember, half of the consideration here is to find a way for Apple to recoup it's investment in LLM. Without creating anti-competitive forces in another market. If you have a different suggestion, or if you think Apple doesn't deserve compensation, make your case.