You listed multiple companies. That's the difference. We debate Android vs. iOS (vs. awesome Linux shenanigans), or Microsoft vs. Apple vs. Linux. Those are

You listed multiple companies. That's the difference. We debate Android vs. iOS (vs. awesome Linux shenanigans), or Microsoft vs. Apple vs. Linux. Those are choices. Most of the market is essentially duopolies, but that's a different issue than a pure monopoly.