And the worst part is, from a societal point of view - it doesnt matter if $companyA wins over $companyB, if the reason they won is that there was more Geico ads than Liberty ads etc.
We allow every space to be overrun with these things, wasting our time and infecting our brains and in the end its zero-sum for the companies and negative-sum for us. No value anywhere is created.
They get paid per ad. Whether the product actually works is not their problem, unless they get a lawsuit. IIRC Facebook did lose a lawsuit over scam ads, but continued doing the process it was sued for, because it's so profitable, and just added a check so those ads don't get shown to regulators.