A visual guide: "A (mostly comprehensive history of Google's ad shading and labeling" https://i.imgur.com/0RxdzBE.png
A visual guide: "A (mostly comprehensive history of Google's ad shading and labeling" https://i.imgur.com/0RxdzBE.png
E.g. https://i.imgur.com/SfomkdQ.png; the second result is a competitor's ad, the third result is the organic result.
[1] https://www.cnbc.com/2019/09/04/google-paid-search-ads-shake...
[2] https://www.nytimes.com/2020/01/17/technology/antitrust-hear...
Edit: Disclosure - I work at Google but this is my own opinion on multi-sided markets
If for example changes to the marketplace makes it harder to determine who is a fraud and who is not or simply making it difficult to determine the quality of products, competition between the companies with the quality products and fraudsters may increase and that would be a bad thing.
https://www.popehat.com/2016/06/14/lawsplainer-its-not-rico-...
It's like saying that you want to regulate what can advertising companies display on billboards, ex. they cannot display competitor's ads nearby your company's offices. Since the billboard space is private and owned by the ad company (similarly to the ad space on Google servers served pages), they get too decide to put there whatever they want (barring free speech limiting regulations).