Within Search + Search Ads you have a platform where Google are/have:
- the sole vendor of a digital asset - ads
- the sole marketplace for that asset
- a closed algorithmic trading system with no public auditing
- no public ledger or auditing showing who bid what
- currently one of the main customers for those ads (advertising their own products)
Along with that you as an advertiser have to install tracking on your site allowing Google to see every transaction, all revenue, every customer, of your business. The level of spying on the advertisers is insane, when seen in combination with the closed source algorithm and market for the ads the potential for manipulation is enormous.
The whole ads platform is built for extracting every last cent of margin from advertisers businesses. It's anticompetitive, monopolistic, and to some extent even a protection racket.
The most important "breakup" needs to be the ads business from everything else, including search. That's going to hurt, and I don't have the answers to how to make it work, but changes are needed.
I suspect a "breakup" isn't on the cards, maybe some strong regulation of online ad marketplaces, ring fencing them from the rest of the business and auditing of the platform?