If you think antitrust has anything to do with why it isn't profitable for a company at Google scale to pay a human being for every one of the hundreds of millions of people who use AdSense to have customer support...
Imagine for a second that, instead of 1 Google, there are tens of thousands of alternatives. Offering good customer support becomes once again a competitive advantage. No sane customer thinks "yep, I want no recourse at all in case of problem so google's profit margins are bigger for the sake of their stakeholders".
Moreover, the cost of doing customer support grows less than linearly thanks to economies of scale, from which Google benefits disproportionally, and here again Google chose profits over quality at the expense of the consumer.