A company worth 3 trillion valuation has implications that many have voted with their wallets that what they are producing is better than the competition. In this case, it's Android that's the competition.
Absurd is subjective. If I built a company that mimics everything that Nvidia/AWS/Apple/Google does at half the price, $4 trillion isn't absurd from my point of view. I just made a bunch of desirable products for half the cost of what people usually pay for.
You'd need statistical analysis to provide objective points of view.
So why would it be ok for 100 million users to be constrained to a "monopoly" store, but if it's a billion, it's not ok? If Apple's failure in AI plays suddenly reduces their active users to 900 million and their market cap to 800 billion, does it become ok to run the App Store the way they are now?
Why not argue on principle rather than laws based on arbitrary thresholds?
Well, see above.
You're the one making an arbitrary distinction based on size of market and/or valuation size, I'm not. Therefore it would be pointless to provide a statistical analysis on valuation size/market size/unit size for something I'm not claiming or doing.
I'm arguing on principle, regardless of size.
Literally your responsibility to back up your arbitrary size argument.