Long blog post but a very valid position. Key paragraph excerpted in italics by me.
First, Google’s behavior lacks any auditability or verifiability; as outsiders, we have no idea what Google is doing under the hood. Second, Google has access to better information to optimize its bidding than any other bidder. That information may not be functionally available to individual employees placing auction bids, but because of the first point (lack of auditability/verifiability), we as outsiders don’t know that either. Third, because all Google bids just involve internal funds transfers and no out-of-pocket cash payments, Google can easily increase departmental budgets to enable more aggressive bidding—after all, if no cash changes hands, it’s just funny money anyway. Fourth, actual ad placement depends on ad quality scores, and Google has acknowledged that it has “exceptionally high Quality Scores” which should automatically give it a bidding advantage over everyone else. And, once again, no one else can audit or verify Google’s self-designated ad quality scores.