> I mean, the position is starting to sound like "anti-trust" really means "The government taxes companies who hold a dominant position in the marketplace."

Anti-trust is overtly about government placing additional restrictions (which, as they have costs, can be viewed as a kind of taxes) on companies with market power so as to limit the degree to which that market power accelerates within its core market and spreads to other markets denying effective choice.

So, you haven't really discovered anything that isn't exactly the overt point of antitrust law.