They get away with that because they know marketing departments don't care - they have ad budgets to spend. Google gives them enough dashboards and excuses to satisfy their bosses. It is still unknown which half of advertising works.
Even if they cared, they have no leverage.
In the financial sector, any market-maker in Google's position would be heavily regulated, and the kind of shit Google pulls would land people in jail. Even without the market manipulation, there's no way a company like Google could operate without a clear separation between departments. The reason for that is that centuries of playing that game have shown that it's the only way to keep market makers honest.
Inevitably some google exec will testify that they "strive to bring the best to their customers and bring a public-good service". By then, everyone will have been warned that this person is unquestionably a swindling weasel.
Companies are prepared to hand over literally hundreds of dollars to persuade Google to direct you to them rather than a competitor.
Whereas most people are fairly used to ignoring banner ads, and the vast majority of ads don't lead directly to a purchase, so they tend to be worth only a few cents at most.
Without decent revenue streams for quality news outlets, the alternative we're slowly heading to is "sponsored" media, with patrons such as Jeff Bezos funding papers like the WP, and distorting their ability to report news accurately, or clickbait media not contributing to news discovery.
This. I tried once and am still a bit confused if I understood it correctly. Google seemed to refuse "too low" bids completely for no other disclosed reason than that they were too low. And the UI was hellbent to make me give google authority to bid on my behalf on googles own ad auction. Like, WTF? Who on their right mind would agree to that? I'd very much like these folks to be my customers. I guarantee, I will sell you whatever (legal) you want, as long as you agree that I can set the price to whatever I want. It just boggles my mind.
(Sorry for the snark but this is a very well studied technique in the offline world that gets completely ignored by online advertisers, rather like AB testing gets mostly ignored by offline advertisers).
Attribution is arguably the biggest challenge in marketing. If you know that someone bought because of an ad you know you can spend more on that ad, if you know no one is buying from it you know not to.
With almost all digital marketing there's some amount of tracking, not necessarily of users, but of ads. When you make a sale you know which ad it came from. Now that's not perfect attribution, users might take a few views to click through, may go direct rather than clicking through, or may click through multiple different ads, but it's pretty good.
With non-digital marketing there's nearly zero information. Billboards, TV adverts, magazines, radio, even podcasts which are digital, etc. The way that attribution is done is based on times of day (did you get a spike after your TV advert aired), or it's based on location (did you get a spike in the area of the billboard). Sometimes discount codes are used for attribution (use code TUBE10 to save £10 on your next order), but those only work for some types of product and users forget more often than not (yes, even with discounts).
Marketing on Google, Facebook, affiliate marketplaces, etc, is all automatable, and more accurate, more precise, and therefore it's easier to understand marketing ROI, and easier to justify more spend.