Similar principle applies to
- review sites like Yelp (interestingly one of Google's loudest antitrust critics)
- domain names (arguably the entire ICANN generic top level domains sell-off)^1; US trademark grantees who fail to take action against confusingly similar domain names risk losing trademark protection
1. The gTLD application alone as $185,000 (https://en.wikipedia.org/wiki/Gtld)
In the case of Google and Yelp, the tech company can manipulate the alleged "algorithm" (read: no humans involve so you cant sue us, haha) behind the scenes and determine the "visibility" of the ad/review.
Ads are the perfect "business model" for tech companies because there is so little scrutiny of the ad services delivered. It is like philanthropy. When we make a donation, we generally do not track what happens to the money afterwards. We get a warm fuzzy feeling from making the donation as it is "doing the right thing". Then we leave the recipient to do as they please. How many companies buy ads on Google because they feel it is "the right thing to do". How many feel their donation was unwarranted after the ads fail to produce results.
Defensive ad purchases, defensive domain name registrations and even defensive gTLD purchases are one side of the coin.
Another is the "winner take all" line-of-thinking (80/20, network effects, etc.) that tech companies worship that they in turn project onto customers. Competing for visibility on a fully searchable web of enormous capacity presupposes (artifically) that visible space is scarce. Ad auctions for the purpose of placing an ad on page one of hundreds of thousands of pages of results. The truth is that many people used to read newspapers from beginning to end. The whole paper, not just page one.
In a physical newspaper, there are ads on many pages. Often there are in fact no ads on page one. How many Google customers are encouraged to purchase ads that will appear on SERP #2 (do they even have ads on SERP #2). Imagine if newspapers tried to create a bidding war for page one of the physical newspaper. With the online versions, it seems that is exactly what happens. Do not blame the newspapers, do not blame Williams-Sonoma, blame the "tech" companies. This only reflects the pathetic "tech" company psychology, not the thinking of the businesses who give them money for online ad services.